Thanks Rodolfo for your quick response. > The specs says that "ref" attribute points to a span of text, that does not mean it must be a <mrk> element, I take it just means that it has to point to an element that contains the text that is being matched. This is somewhat I initially thought and I thought it make sense to point <segment> element. However, I realized that the original intent was not to limit a text span of match can be in <target> element, I started thinking the spec really meant exact text span specified. For for example: <?xml version = "1.0" encoding = "UTF-8" ?> <xliff xmlns = "urn:oasis:names:tc:xliff:document:2.0" version = "2.0" srcLang = "en" xmlns:fs = "urn:oasis:names:tc:xliff:fs:2.0" xml:space = "preserve" xmlns:mtc = "urn:oasis:names:tc:xliff:matches:2.0" trgLang = "fr" > <file id = "f1" > <unit id = "u1" > <mtc:matches> <mtc:match id = "tc1" ref = "#s1" similarity = "65" > <source> Please check the output. </source> <target> Veuillez vérifier la sortie. </target> </mtc:match> </mtc:matches> <segment id = "s1" > <source> Please check the results. </source> <target> Veuillez vérifier les résultats. </target> </segment> </unit> </file> </xliff> If we allow <segment> can be referenced from <mtc:match> in bi-lingual XLIFF, it becomes ambiguous whether match/similarity is coming from the <source> value or the <target> value. I think typical translation service application using XLIFF would do translation memory look up for each <segment>. If I were author of the spec and if segment element can be used for target span of text, I would not put example found in 5.1.4 - <unit id = "1" > <mtc:matches> <mtc:match ref = "#m1" > <source> He is my friend. </source> <target> Il est mon ami. </target> </mtc:match> <mtc:match ref = "#m1" > <source> He is my best friend. </source> <target> Il est mon meilleur ami. </target> </mtc:match> </mtc:matches> <segment> <source><mrk id = "m1" type = "mtc:match" > He is my friend. </mrk></source> </segment> <segment> <source> Yet, I barely see him. </source> </segment> </unit> Use of <mrk> will allow us to annotate sub-string of source/target value. If you can use a segment ID for the reference, the use of segment ID looks more natural choice. But this example uses <mrk> to enclose entire span of text in <source> element. I also carefully looked at the term "span of text" "spanning" etc. in the specification. I feel these terms are specifically used for text value (including inline elements). The segment element is a container of source/target element, so I feel segment element does not specify "span of text". If the original intention was to allow segment ID reference, then the spec should state - "points to a span of text or a container..." -Yoshito