XMI12 — UML: Using public identifiers to denote DTDs

n order to exchange UML models by means of XMI, using an external DTD
subset is common to avoid including the DTD into each document. Usage
of SYSTEM identifiers should be avoided, since location of the DTD
might vary between installations.

To detect that a document is based on a well-known DTD (e.g. the XMI
1.1 UML 1.4 DTD), a formal public identifier should be used. Since it
is likely that OMG will need a number of public identifiers, it would
be best if OMG could register an owner ID with ISO. With that, a
DOCTYPE declaration could read

<!DOCTYPE XMI PUBLIC "+//<omg>//DTD UML 1.4 XMI 1.1//EN">

The procedure for registering public identifiers is defined in ISO
9070; registration authority is ANSI (and delegated to
GCA). Alternatively, an owner identifier can be derived through an ISO
6523 organization identifier (authority is BSI), or using the Annex J
IDN scheme.