The WWP encodes indicators of repetition by using the sameAs= attribute. Indicators of repetition include words like “ditto” (for instance, in subscriber lists), “etc.” (for instance, in choruses or refrains), or “ibid.” (in bibliographic references). In each case, the repeater word (ditto, ibid...) should be encoded with an element whose sameAs= attribute should point to the ID of the element whose content is being repeated. If no element is already conveniently present (such as <persName> or <placeName>) then <seg> should be used. Thus, in the case of a subscriber list with several subscribers from the same town:
<item><persName key="JAtkinson.xyz">Mr. Joseph Atkinson</>
<item><persName key="IAtkinson.wqi">Mr. Isaac Atkinson</>
Where “ditto” is used in place of a name or place name, we encode it as follows:
<persName sameAs="[point to ID of the referent; this is the instance where the actual name appears, not the previous ditto]">ditto</persName>
<placeName sameAs="[point to ID of the referent]">ditto</placeName>
Phrases which indicate repetition, such as “ditto” or “etc.” (in choruses) or “ibid.” (in bibliographic references) should not be expanded using <abbr>.
If phrases such as “2 copies” are dittoed, they can also take the sameAs= attribute on the element that is used to encode them (in this case the <measure> element).