OASIS Darwin Information Typing Architecture (DITA) TC

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  • 1.  MUST, SHOULD, and MAY, some key words from RFC 2119

    Posted 10-02-2007 18:08
    
    
    
    
    
    
    
    
    
    
    
    Included below are some words taken from RFC 2119 on “Key words for use in RFCs to Indicate Requirement Levels". I think we are going to need to use this or a similar approach in the DITA standard.
     
    1. MUST   This word, or the terms "REQUIRED" or "SHALL", mean that the
       definition is an absolute requirement of the specification.
     
    2. MUST NOT   This phrase, or the phrase "SHALL NOT", mean that the
       definition is an absolute prohibition of the specification.
     
    3. SHOULD   This word, or the adjective "RECOMMENDED", mean that there
       may exist valid reasons in particular circumstances to ignore a
       particular item, but the full implications must be understood and
       carefully weighed before choosing a different course.
     
    4. SHOULD NOT   This phrase, or the phrase "NOT RECOMMENDED" mean that
       there may exist valid reasons in particular circumstances when the
       particular behavior is acceptable or even useful, but the full
       implications should be understood and the case carefully weighed
       before implementing any behavior described with this label.
     
    5. MAY   This word, or the adjective "OPTIONAL", mean that an item is
       truly optional.  One vendor may choose to include the item because a
       particular marketplace requires it or because the vendor feels that
       it enhances the product while another vendor may omit the same item.
       An implementation which does not include a particular option MUST be
       prepared to interoperate with another implementation which does
       include the option, though perhaps with reduced functionality. In the
       same vein an implementation which does include a particular option
       MUST be prepared to interoperate with another implementation which
       does not include the option (except, of course, for the feature the
       option provides.)
     
    To see the full RFC (its short), see:  http://www.ietf.org/rfc/rfc2119.txt?number=2119
     
    Note that as we split the DITA Specification into multiple specifications, that an entire specification may be REQUIRED, RECOMMENDED, or OPTIONAL, but within the individual specifications there will be items that are REQUIRED, RECOMMENDED or which are OPTIONAL.
     
    So, if I take the summary from Michael’s recent note:
    -          everyone needs to support the core; 
    -          specialized support (beyond core defaults) for the specialized parts of the spec are optional but encouraged, and should represent an established user community;
    -          specialized support (beyond core defaults or standard specialization defaults) for non-standardized user specializations are up to the user or their partners to provide
     
    I can rewrite it using the RFC terms as follows:
    -          everyone MUST support the core; 
    -          specialized support (beyond core defaults) for the specialized parts of the spec are RECOMMENDED, and MUST represent an established user community;
    -          specialized support (beyond core defaults or standard specialization defaults) for non-standardized user specializations is OPTIONAL and up to the user or their partners to provide.
     
    Michael, how did I do?
     
     -Jeff


  • 2.  Re: [dita] MUST, SHOULD, and MAY, some key words from RFC 2119

    Posted 10-02-2007 18:15

    Looks good, Jeff - with the caveat though that even though the core is MUST and the specializations are RECOMMENDED or OPTIONAL, a specialization may introduce behavior that overrides the core.

    In other words, all behavior, core and specialized, is overrideable.

    Michael Priestley
    Lead IBM DITA Architect
    mpriestl@ca.ibm.com
    http://dita.xml.org/blog/25



    "Ogden, Jeff" <jogden@ptc.com>

    10/02/2007 02:08 PM

    To
    <dita@lists.oasis-open.org>
    cc
    Subject
    [dita] MUST, SHOULD, and MAY, some key words from RFC 2119





    Included below are some words taken from RFC 2119 on “Key words for use in RFCs to Indicate Requirement Levels". I think we are going to need to use this or a similar approach in the DITA standard.
     
    1. MUST   This word, or the terms "REQUIRED" or "SHALL", mean that the
       definition is an absolute requirement of the specification.
     
    2. MUST NOT   This phrase, or the phrase "SHALL NOT", mean that the
       definition is an absolute prohibition of the specification.
     
    3. SHOULD   This word, or the adjective "RECOMMENDED", mean that there
       may exist valid reasons in particular circumstances to ignore a
       particular item, but the full implications must be understood and
       carefully weighed before choosing a different course.
     
    4. SHOULD NOT   This phrase, or the phrase "NOT RECOMMENDED" mean that
       there may exist valid reasons in particular circumstances when the
       particular behavior is acceptable or even useful, but the full
       implications should be understood and the case carefully weighed
       before implementing any behavior described with this label.
     
    5. MAY   This word, or the adjective "OPTIONAL", mean that an item is
       truly optional.  One vendor may choose to include the item because a
       particular marketplace requires it or because the vendor feels that
       it enhances the product while another vendor may omit the same item.
       An implementation which does not include a particular option MUST be
       prepared to interoperate with another implementation which does
       include the option, though perhaps with reduced functionality. In the
       same vein an implementation which does include a particular option
       MUST be prepared to interoperate with another implementation which
       does not include the option (except, of course, for the feature the
       option provides.)
     
    To see the full RFC (its short), see:  http://www.ietf.org/rfc/rfc2119.txt?number=2119
     
    Note that as we split the DITA Specification into multiple specifications, that an entire specification may be REQUIRED, RECOMMENDED, or OPTIONAL, but within the individual specifications there will be items that are REQUIRED, RECOMMENDED or which are OPTIONAL.
     
    So, if I take the summary from Michael’s recent note:
    -          everyone needs to support the core;
    -          specialized support (beyond core defaults) for the specialized parts of the spec are optional but encouraged, and should represent an established user community;
    -          specialized support (beyond core defaults or standard specialization defaults) for non-standardized user specializations are up to the user or their partners to provide
     
    I can rewrite it using the RFC terms as follows:
    -          everyone MUST support the core;
    -          specialized support (beyond core defaults) for the specialized parts of the spec are RECOMMENDED, and MUST represent an established user community;
    -          specialized support (beyond core defaults or standard specialization defaults) for non-standardized user specializations is OPTIONAL and up to the user or their partners to provide.
     
    Michael, how did I do?
     
     -Jeff


  • 3.  RE: [dita] MUST, SHOULD, and MAY, some key words from RFC 2119

    Posted 10-02-2007 18:24
    
    
    
    
    
    If I'm not misunderstanding what you're saying, Michael, that is the most unusual definition of "standard" I have ever seen in my quarter century of working on standards.
     
    Then what does it mean to be MUST in the core DITA standard?
     
    More to the point, what is the core DITA standard standardizing?
     
    paul


    From: Michael Priestley [mailto:mpriestl@ca.ibm.com]
    Sent: Tuesday, 2007 October 02 13:15
    To: Ogden, Jeff
    Cc: dita@lists.oasis-open.org
    Subject: Re: [dita] MUST, SHOULD, and MAY, some key words from RFC 2119


    Looks good, Jeff - with the caveat though that even though the core is MUST and the specializations are RECOMMENDED or OPTIONAL, a specialization may introduce behavior that overrides the core.

    In other words, all behavior, core and specialized, is overrideable.


  • 4.  RE: [dita] MUST, SHOULD, and MAY, some key words from RFC 2119

    Posted 10-02-2007 18:37

    MUST means that an implementer MUST provide this default behavior.

    I think the alternative is to render specialization powerless to introduce new behaviors that conflict with the base. Which, given that half the motivation for specialization is to do something beyond what the base does, would render useless about half the specializations already out there.

    Also note that the existing spec, since 1.0, has a whole section on how to manage processing overrides. If we want to disallow processing overrides, that's a funny thing to have in the spec.

    One of the main points of specialization is that all behavior is default, and may be overridden by a specializer. This is nothing new, so I think/hope we're just talking past each other.

    Michael Priestley
    Lead IBM DITA Architect
    mpriestl@ca.ibm.com
    http://dita.xml.org/blog/25



    "Grosso, Paul" <pgrosso@ptc.com>

    10/02/2007 02:23 PM

    To
    <dita@lists.oasis-open.org>
    cc
    Subject
    RE: [dita] MUST, SHOULD, and MAY, some key words from RFC 2119





    If I'm not misunderstanding what you're saying, Michael, that is the most unusual definition of "standard" I have ever seen in my quarter century of working on standards.
     
    Then what does it mean to be MUST in the core DITA standard?
     
    More to the point, what is the core DITA standard standardizing?
     
    paul


    From: Michael Priestley [mailto:mpriestl@ca.ibm.com]
    Sent:
    Tuesday, 2007 October 02 13:15
    To:
    Ogden, Jeff
    Cc:
    dita@lists.oasis-open.org
    Subject:
    Re: [dita] MUST, SHOULD, and MAY, some key words from RFC 2119



    Looks good, Jeff - with the caveat though that even though the core is MUST and the specializations are RECOMMENDED or OPTIONAL, a specialization may introduce behavior that overrides the core.


    In other words, all behavior, core and specialized, is overrideable.



  • 5.  RE: [dita] MUST, SHOULD, and MAY, some key words from RFC 2119

    Posted 10-02-2007 18:31
    
    
    
    
    
    
    
    
    
    
    

    Michael wrote:

    > In other words, all behavior, core and specialized, is overrideable.

     

    This is the subject of the discussion (item #4 from my previous note) that we plan to have. The fundamental question that we need to answer is, is all behavior overrideable, that is, is everything either RECOMMENDED or OPTIONAL, or are some things truly REQUIRED?

     

    Or stated another way, the core as a whole is REQUIRED, but individual items within the core may be REQUIRED, RECOMMENDED, or OPTIONAL with respect to specializations. 

     

    This doesn’t really get interesting until we get down to specific cases and we have to figure out when to use MUST / REQUIRED, SHOULD / RECOMMENDED, and MAY / OPTIONAL

     

        -Jeff

     


    From: Michael Priestley [mailto:mpriestl@ca.ibm.com]
    Sent: Tuesday, October 02, 2007 2:15 PM
    To: Ogden, Jeff
    Cc: dita@lists.oasis-open.org
    Subject: Re: [dita] MUST, SHOULD, and MAY, some key words from RFC 2119

     


    Looks good, Jeff - with the caveat though that even though the core is MUST and the specializations are RECOMMENDED or OPTIONAL, a specialization may introduce behavior that overrides the core.

    In other words, all behavior, core and specialized, is overrideable.

    Michael Priestley
    Lead IBM DITA Architect
    mpriestl@ca.ibm.com
    http://dita.xml.org/blog/25


    "Ogden, Jeff" <jogden@ptc.com>

    10/02/2007 02:08 PM

    To

    <dita@lists.oasis-open.org>

    cc

     

    Subject

    [dita] MUST, SHOULD, and MAY, some key words from RFC 2119

     

     

     




    Included below are some words taken from RFC 2119 on “Key words for use in RFCs to Indicate Requirement Levels". I think we are going to need to use this or a similar approach in the DITA standard.
     
    1. MUST   This word, or the terms "REQUIRED" or "SHALL", mean that the
       definition is an absolute requirement of the specification.
     
    2. MUST NOT   This phrase, or the phrase "SHALL NOT", mean that the
       definition is an absolute prohibition of the specification.
     
    3. SHOULD   This word, or the adjective "RECOMMENDED", mean that there
       may exist valid reasons in particular circumstances to ignore a
       particular item, but the full implications must be understood and
       carefully weighed before choosing a different course.
     
    4. SHOULD NOT   This phrase, or the phrase "NOT RECOMMENDED" mean that
       there may exist valid reasons in particular circumstances when the
       particular behavior is acceptable or even useful, but the full
       implications should be understood and the case carefully weighed
       before implementing any behavior described with this label.
     
    5. MAY   This word, or the adjective "OPTIONAL", mean that an item is
       truly optional.  One vendor may choose to include the item because a
       particular marketplace requires it or because the vendor feels that
       it enhances the product while another vendor may omit the same item.
       An implementation which does not include a particular option MUST be
       prepared to interoperate with another implementation which does
       include the option, though perhaps with reduced functionality. In the
       same vein an implementation which does include a particular option
       MUST be prepared to interoperate with another implementation which
       does not include the option (except, of course, for the feature the
       option provides.)
     
    To see the full RFC (its short), see:  http://www.ietf.org/rfc/rfc2119.txt?number=2119
     
    Note that as we split the DITA Specification into multiple specifications, that an entire specification may be REQUIRED, RECOMMENDED, or OPTIONAL, but within the individual specifications there will be items that are REQUIRED, RECOMMENDED or which are OPTIONAL.
     
    So, if I take the summary from Michael’s recent note:
    -          everyone needs to support the core;
    -          specialized support (beyond core defaults) for the specialized parts of the spec are optional but encouraged, and should represent an established user community;
    -          specialized support (beyond core defaults or standard specialization defaults) for non-standardized user specializations are up to the user or their partners to provide
     
    I can rewrite it using the RFC terms as follows:
    -          everyone MUST support the core;
    -          specialized support (beyond core defaults) for the specialized parts of the spec are RECOMMENDED, and MUST represent an established user community;
    -          specialized support (beyond core defaults or standard specialization defaults) for non-standardized user specializations is OPTIONAL and up to the user or their partners to provide.
     
    Michael, how did I do?
     
     -Jeff



  • 6.  RE: [dita] MUST, SHOULD, and MAY, some key words from RFC 2119

    Posted 10-02-2007 18:42

    Yes, I think specific examples are good. Here are some examples off the top of my head for overriding existing core behaviors:

    - conref: override current behavior to limit reuse to a particular set of targets (eg only allow reuse from topics in a "/reuse" subdirectory)
    - map-based linking: create breadcrumb links (to all ancestors) instead of just parent links
    - link resolution: pull the shortdesc for APIRef topics from their syntax as well as their shortdesc

    Some of the overrides could be driven by specializations, some could just be driven by business process requirements.

    Michael Priestley
    Lead IBM DITA Architect
    mpriestl@ca.ibm.com
    http://dita.xml.org/blog/25



    "Ogden, Jeff" <jogden@ptc.com>

    10/02/2007 02:30 PM

    To
    Michael Priestley/Toronto/IBM@IBMCA
    cc
    <dita@lists.oasis-open.org>
    Subject
    RE: [dita] MUST, SHOULD, and MAY, some key words from RFC 2119





    Michael wrote:
    > In other words, all behavior, core and specialized, is overrideable.
     
    This is the subject of the discussion (item #4 from my previous note) that we plan to have. The fundamental question that we need to answer is, is all behavior overrideable, that is, is everything either RECOMMENDED or OPTIONAL, or are some things truly REQUIRED?
     
    Or stated another way, the core as a whole is REQUIRED, but individual items within the core may be REQUIRED, RECOMMENDED, or OPTIONAL with respect to specializations.  
     
    This doesn’t really get interesting until we get down to specific cases and we have to figure out when to use MUST / REQUIRED, SHOULD / RECOMMENDED, and MAY / OPTIONAL
     
        -Jeff
     



    From: Michael Priestley [mailto:mpriestl@ca.ibm.com]
    Sent:
    Tuesday, October 02, 2007 2:15 PM
    To:
    Ogden, Jeff
    Cc:
    dita@lists.oasis-open.org
    Subject:
    Re: [dita] MUST, SHOULD, and MAY, some key words from RFC 2119

     

    Looks good, Jeff - with the caveat though that even though the core is MUST and the specializations are RECOMMENDED or OPTIONAL, a specialization may introduce behavior that overrides the core.


    In other words, all behavior, core and specialized, is overrideable.


    Michael Priestley
    Lead IBM DITA Architect
    mpriestl@ca.ibm.com
    http://dita.xml.org/blog/25

    "Ogden, Jeff" <jogden@ptc.com>

    10/02/2007 02:08 PM


    To
    <dita@lists.oasis-open.org>
    cc
     
    Subject
    [dita] MUST, SHOULD, and MAY, some key words from RFC 2119

     


       





    Included below are some words taken from RFC 2119 on “Key words for use in RFCs to Indicate Requirement Levels". I think we are going to need to use this or a similar approach in the DITA standard.

     
    1. MUST   This word, or the terms "REQUIRED" or "SHALL", mean that the

      definition is an absolute requirement of the specification.

     
    2. MUST NOT   This phrase, or the phrase "SHALL NOT", mean that the

      definition is an absolute prohibition of the specification.

     
    3. SHOULD   This word, or the adjective "RECOMMENDED", mean that there

      may exist valid reasons in particular circumstances to ignore a

      particular item, but the full implications must be understood and

      carefully weighed before choosing a different course.

     
    4. SHOULD NOT   This phrase, or the phrase "NOT RECOMMENDED" mean that

      there may exist valid reasons in particular circumstances when the

      particular behavior is acceptable or even useful, but the full

      implications should be understood and the case carefully weighed

      before implementing any behavior described with this label.

     
    5. MAY   This word, or the adjective "OPTIONAL", mean that an item is

      truly optional.  One vendor may choose to include the item because a

      particular marketplace requires it or because the vendor feels that

      it enhances the product while another vendor may omit the same item.

      An implementation which does not include a particular option MUST be

      prepared to interoperate with another implementation which does

      include the option, though perhaps with reduced functionality. In the

      same vein an implementation which does include a particular option

      MUST be prepared to interoperate with another implementation which

      does not include the option (except, of course, for the feature the

      option provides.)

     
    To see the full RFC (its short), see:  
    http://www.ietf.org/rfc/rfc2119.txt?number=2119
     
    Note that as we split the DITA Specification into multiple specifications, that an entire specification may be REQUIRED, RECOMMENDED, or OPTIONAL, but within the individual specifications there will be items that are REQUIRED, RECOMMENDED or which are OPTIONAL.

     
    So, if I take the summary from Michael’s recent note:

    -
             everyone needs to support the core;
    -
             specialized support (beyond core defaults) for the specialized parts of the spec are optional but encouraged, and should represent an established user community;
    -
             specialized support (beyond core defaults or standard specialization defaults) for non-standardized user specializations are up to the user or their partners to provide
     
    I can rewrite it using the RFC terms as follows:

    -
             everyone MUST support the core;
    -
             specialized support (beyond core defaults) for the specialized parts of the spec are RECOMMENDED, and MUST represent an established user community;
    -
             specialized support (beyond core defaults or standard specialization defaults) for non-standardized user specializations is OPTIONAL and up to the user or their partners to provide.
     
    Michael, how did I do?

     
    -Jeff



  • 7.  RE: [dita] MUST, SHOULD, and MAY, some key words from RFC 2119

    Posted 10-02-2007 19:01
    
    
    
    
    
    
    
    
    
    
    

    OK and here are some examples of overrides that I don’t think we should allow:

     

    • Allowing a reference of the form “#elementid” to reference sub-topic content.
    • Allowing new attributes in specializations that are not based on @props or @base.
    • Allowing specializations to give new meanings to or ignore the meanings of existing attribute/value pairs (scope=”external”).
    • Allowing specializations to ignore @lockmeta.
    • Allowing properties that normally cascade from a map to a topic to not cascade depending on the specializations in use.

     

    I don’t think this is an all or nothing decision.  I think we can and should apply the key words MUST, SHOULD, and MAY differently to different items in the DITA Standard.

     

       -Jeff

     


    From: Michael Priestley [mailto:mpriestl@ca.ibm.com]
    Sent: Tuesday, October 02, 2007 2:41 PM
    To: Ogden, Jeff
    Cc: dita@lists.oasis-open.org
    Subject: RE: [dita] MUST, SHOULD, and MAY, some key words from RFC 2119

     


    Yes, I think specific examples are good. Here are some examples off the top of my head for overriding existing core behaviors:

    - conref: override current behavior to limit reuse to a particular set of targets (eg only allow reuse from topics in a "/reuse" subdirectory)
    - map-based linking: create breadcrumb links (to all ancestors) instead of just parent links
    - link resolution: pull the shortdesc for APIRef topics from their syntax as well as their shortdesc

    Some of the overrides could be driven by specializations, some could just be driven by business process requirements.

    Michael Priestley
    Lead IBM DITA Architect
    mpriestl@ca.ibm.com
    http://dita.xml.org/blog/25


    "Ogden, Jeff" <jogden@ptc.com>

    10/02/2007 02:30 PM

    To

    Michael Priestley/Toronto/IBM@IBMCA

    cc

    <dita@lists.oasis-open.org>

    Subject

    RE: [dita] MUST, SHOULD, and MAY, some key words from RFC 2119

     

     

     




    Michael wrote:
    > In other words, all behavior, core and specialized, is overrideable.
     
    This is the subject of the discussion (item #4 from my previous note) that we plan to have. The fundamental question that we need to answer is, is all behavior overrideable, that is, is everything either RECOMMENDED or OPTIONAL, or are some things truly REQUIRED?
     
    Or stated another way, the core as a whole is REQUIRED, but individual items within the core may be REQUIRED, RECOMMENDED, or OPTIONAL with respect to specializations.  
     
    This doesn’t really get interesting until we get down to specific cases and we have to figure out when to use MUST / REQUIRED, SHOULD / RECOMMENDED, and MAY / OPTIONAL
     
        -Jeff
     

     



    From: Michael Priestley [mailto:mpriestl@ca.ibm.com]
    Sent:
    Tuesday, October 02, 2007 2:15 PM
    To:
    Ogden, Jeff
    Cc:
    dita@lists.oasis-open.org
    Subject:
    Re: [dita] MUST, SHOULD, and MAY, some key words from RFC 2119

     

    Looks good, Jeff - with the caveat though that even though the core is MUST and the specializations are RECOMMENDED or OPTIONAL, a specialization may introduce behavior that overrides the core.


    In other words, all behavior, core and specialized, is overrideable.


    Michael Priestley
    Lead IBM DITA Architect
    mpriestl@ca.ibm.com
    http://dita.xml.org/blog/25

    "Ogden, Jeff" <jogden@ptc.com>

    10/02/2007 02:08 PM

     

    To

    <dita@lists.oasis-open.org>

    cc

     

    Subject

    [dita] MUST, SHOULD, and MAY, some key words from RFC 2119


     

     

     

     





    Included below are some words taken from RFC 2119 on “Key words for use in RFCs to Indicate Requirement Levels". I think we are going to need to use this or a similar approach in the DITA standard.

     
    1. MUST   This word, or the terms "REQUIRED" or "SHALL", mean that the

      definition is an absolute requirement of the specification.

     
    2. MUST NOT   This phrase, or the phrase "SHALL NOT", mean that the

      definition is an absolute prohibition of the specification.

     
    3. SHOULD   This word, or the adjective "RECOMMENDED", mean that there

      may exist valid reasons in particular circumstances to ignore a

      particular item, but the full implications must be understood and

      carefully weighed before choosing a different course.

     
    4. SHOULD NOT   This phrase, or the phrase "NOT RECOMMENDED" mean that

      there may exist valid reasons in particular circumstances when the

      particular behavior is acceptable or even useful, but the full

      implications should be understood and the case carefully weighed

      before implementing any behavior described with this label.

     
    5. MAY   This word, or the adjective "OPTIONAL", mean that an item is

      truly optional.  One vendor may choose to include the item because a

      particular marketplace requires it or because the vendor feels that

      it enhances the product while another vendor may omit the same item.

      An implementation which does not include a particular option MUST be

      prepared to interoperate with another implementation which does

      include the option, though perhaps with reduced functionality. In the

      same vein an implementation which does include a particular option

      MUST be prepared to interoperate with another implementation which

      does not include the option (except, of course, for the feature the

      option provides.)

     
    To see the full RFC (its short), see:  
    http://www.ietf.org/rfc/rfc2119.txt?number=2119
     
    Note that as we split the DITA Specification into multiple specifications, that an entire specification may be REQUIRED, RECOMMENDED, or OPTIONAL, but within the individual specifications there will be items that are REQUIRED, RECOMMENDED or which are OPTIONAL.

     
    So, if I take the summary from Michael’s recent note:

    -
             everyone needs to support the core;
    -
             specialized support (beyond core defaults) for the specialized parts of the spec are optional but encouraged, and should represent an established user community;
    -
             specialized support (beyond core defaults or standard specialization defaults) for non-standardized user specializations are up to the user or their partners to provide
     
    I can rewrite it using the RFC terms as follows:

    -
             everyone MUST support the core;
    -
             specialized support (beyond core defaults) for the specialized parts of the spec are RECOMMENDED, and MUST represent an established user community;
    -
             specialized support (beyond core defaults or standard specialization defaults) for non-standardized user specializations is OPTIONAL and up to the user or their partners to provide.
     
    Michael, how did I do?

     
    -Jeff



  • 8.  RE: [dita] MUST, SHOULD, and MAY, some key words from RFC 2119

    Posted 10-02-2007 19:25

    Thanks for the examples - adding thoughts to them below
    Michael Priestley
    Lead IBM DITA Architect
    mpriestl@ca.ibm.com
    http://dita.xml.org/blog/25



    "Ogden, Jeff" <jogden@ptc.com>

    10/02/2007 03:01 PM

    To
    Michael Priestley/Toronto/IBM@IBMCA
    cc
    <dita@lists.oasis-open.org>
    Subject
    RE: [dita] MUST, SHOULD, and MAY, some key words from RFC 2119





    OK and here are some examples of overrides that I don’t think we should allow:
     
    • Allowing a reference of the form “#elementid” to reference sub-topic content.
      MP: if someone's using a CMS and assigning GUIDs to every element, they may actually have one unique identifier per element, rather than per topic+element. That said, I see your point - it would be preferable for the tool to externalize the reference as properly formed DITA, even if it is internally managed differently. I can easily see the syntax of the href and conref attributes, along with the domains and class attributes, as being immutable. That said, if someone wants to override what they do with that syntax (for example, fetching the linktext for the subelement from its parent topic), I would think that's reasonable.
    • Allowing new attributes in specializations that are not based on @props or @base.
      MP: that's not a behavior, so is in a different bucket in my mind. The doctype is a valid specialization or not regardless of what processing is done with the doctype.
    • Allowing specializations to give new meanings to or ignore the meanings of existing attribute/value pairs (scope=”external”).
      MP: maybe there's a difference here between "meaning" and "behavior". For example, current behavior for scope="external" might be to open up a new browser window - but in a particular delivery context they might actually want to popup an intermediate window that says "you're leaving the website and everything after this is unwarrantied" or something. Not changing the meaning, but definitely changing the behavior.
    • Allowing specializations to ignore @lockmeta.
      MP: I can imagine a draft review process that pulled in "author" info from the target topics, even though lockmeta was set, because they wanted to use a single map for both review and for final publication, and they only wanted the author info for review... So in this case, I am imagining a process that would ignore lockmeta to do a particular metadata fetch based on business need rather than specialization.
    • Allowing properties that normally cascade from a map to a topic to not cascade depending on the specializations in use.
      MP: if a group was doing extensive customization in a map, and was tracking authorship of the map at a chapter level, I can imagine overriding the normal cascade of metadata from map to topic to stop author from cascading and implying authorship of the actual topics rather than of the referencing map sections.  Again, a customization not based on specialization, but still definitely an override of default behavior.
     
    I don’t think this is an all or nothing decision.  I think we can and should apply the key words MUST, SHOULD, and MAY differently to different items in the DITA Standard.

    MP: I can definitely see the point of preserving the syntax and meaning of our core attributes - but not sure how much of subsequent behavior we can really standardize beyond "don't be an idiot".  For example, we have a "<b>" element that should be rendered as bold - but if someone has a compelling reason to override that (like bold text has been reserved for warnings only), then I think adopters should have the freedom to define their own output processing, even when it deviates from what's in the spec.
     
       -Jeff
     



    From: Michael Priestley [mailto:mpriestl@ca.ibm.com]
    Sent:
    Tuesday, October 02, 2007 2:41 PM
    To:
    Ogden, Jeff
    Cc:
    dita@lists.oasis-open.org
    Subject:
    RE: [dita] MUST, SHOULD, and MAY, some key words from RFC 2119

     

    Yes, I think specific examples are good. Here are some examples off the top of my head for overriding existing core behaviors:


    - conref: override current behavior to limit reuse to a particular set of targets (eg only allow reuse from topics in a "/reuse" subdirectory)

    - map-based linking: create breadcrumb links (to all ancestors) instead of just parent links

    - link resolution: pull the shortdesc for APIRef topics from their syntax as well as their shortdesc


    Some of the overrides could be driven by specializations, some could just be driven by business process requirements.


    Michael Priestley
    Lead IBM DITA Architect
    mpriestl@ca.ibm.com
    http://dita.xml.org/blog/25

    "Ogden, Jeff" <jogden@ptc.com>

    10/02/2007 02:30 PM


    To
    Michael Priestley/Toronto/IBM@IBMCA
    cc
    <dita@lists.oasis-open.org>
    Subject
    RE: [dita] MUST, SHOULD, and MAY, some key words from RFC 2119

     


       





    Michael wrote:

    > In other words, all behavior, core and specialized, is overrideable.

     
    This is the subject of the discussion (item #4 from my previous note) that we plan to have. The fundamental question that we need to answer is, is all behavior overrideable, that is, is everything either RECOMMENDED or OPTIONAL, or are some things truly REQUIRED?

     
    Or stated another way, the core as a whole is REQUIRED, but individual items within the core may be REQUIRED, RECOMMENDED, or OPTIONAL with respect to specializations.  

     
    This doesn’t really get interesting until we get down to specific cases and we have to figure out when to use MUST / REQUIRED, SHOULD / RECOMMENDED, and MAY / OPTIONAL

     
       -Jeff

     

     



    From:
    Michael Priestley [mailto:mpriestl@ca.ibm.com]
    Sent:
    Tuesday, October 02, 2007 2:15 PM
    To:
    Ogden, Jeff
    Cc:
    dita@lists.oasis-open.org
    Subject:
    Re: [dita] MUST, SHOULD, and MAY, some key words from RFC 2119

     


    Looks good, Jeff - with the caveat though that even though the core is MUST and the specializations are RECOMMENDED or OPTIONAL, a specialization may introduce behavior that overrides the core.


    In other words, all behavior, core and specialized, is overrideable.


    Michael Priestley
    Lead IBM DITA Architect
    mpriestl@ca.ibm.com
    http://dita.xml.org/blog/25

    "Ogden, Jeff" <jogden@ptc.com>

    10/02/2007 02:08 PM

     


    To
    <dita@lists.oasis-open.org>
    cc
     
    Subject
    [dita] MUST, SHOULD, and MAY, some key words from RFC 2119


     

     


       





    Included below are some words taken from RFC 2119 on “Key words for use in RFCs to Indicate Requirement Levels". I think we are going to need to use this or a similar approach in the DITA standard.


    1. MUST   This word, or the terms "REQUIRED" or "SHALL", mean that the

     definition is an absolute requirement of the specification.


    2. MUST NOT   This phrase, or the phrase "SHALL NOT", mean that the

     definition is an absolute prohibition of the specification.


    3. SHOULD   This word, or the adjective "RECOMMENDED", mean that there

     may exist valid reasons in particular circumstances to ignore a

     particular item, but the full implications must be understood and

     carefully weighed before choosing a different course.


    4. SHOULD NOT   This phrase, or the phrase "NOT RECOMMENDED" mean that

     there may exist valid reasons in particular circumstances when the

     particular behavior is acceptable or even useful, but the full

     implications should be understood and the case carefully weighed

     before implementing any behavior described with this label.


    5. MAY   This word, or the adjective "OPTIONAL", mean that an item is

     truly optional.  One vendor may choose to include the item because a

     particular marketplace requires it or because the vendor feels that

     it enhances the product while another vendor may omit the same item.

     An implementation which does not include a particular option MUST be

     prepared to interoperate with another implementation which does

     include the option, though perhaps with reduced functionality. In the

     same vein an implementation which does include a particular option

     MUST be prepared to interoperate with another implementation which

     does not include the option (except, of course, for the feature the

     option provides.)


    To see the full RFC (its short), see:  
    http://www.ietf.org/rfc/rfc2119.txt?number=2119

    Note that as we split the DITA Specification into multiple specifications, that an entire specification may be REQUIRED, RECOMMENDED, or OPTIONAL, but within the individual specifications there will be items that are REQUIRED, RECOMMENDED or which are OPTIONAL.


    So, if I take the summary from Michael’s recent note:

    -
             everyone needs to support the core;
    -
             specialized support (beyond core defaults) for the specialized parts of the spec are optional but encouraged, and should represent an established user community;
    -
             specialized support (beyond core defaults or standard specialization defaults) for non-standardized user specializations are up to the user or their partners to provide

    I can rewrite it using the RFC terms as follows:

    -
             everyone MUST support the core;
    -
             specialized support (beyond core defaults) for the specialized parts of the spec are RECOMMENDED, and MUST represent an established user community;
    -
             specialized support (beyond core defaults or standard specialization defaults) for non-standardized user specializations is OPTIONAL and up to the user or their partners to provide.

    Michael, how did I do?


    -Jeff