An API to an FDL used by Clients to access or contribute Texts must provide a means of realizing Abstract Identifiers as concrete values for the duration of a Session. The fact that across different sessions, the representation of identifiers internal to the FDL is likely to change may be seen as the enforcement of abstractness.
Of course, the method for representing the structure of Texts for communication with the FDL is another aspect of such an API. An XML presentation of Texts would be a reasonable candidate.
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