The composer_sysid function returns the composer handle for the specified composer type associated with this document. The system ID acts as a handle.

The type parameter specifies the type of composer. The type is specified by the Compose element's type attribute in the DCF file for doc.

The doc parameter specifies the document for which the composer handle is being created. If doc is not specified, the current document is used.

The associated composer name is defined by the Compose element's config attribute in the DCF file. This attribute may be a path to a CCF file or the CCF file name. If the file name does not specify the .ccf extension, the file name is concatenated to the type name to construct the composer name.

If the composer name is not an absolute path, then the doctype directory is searched for the specified file. If the file is not found, the set composerpath directories are searched in order. If a matching file is found, its full cannonicalized path becomes the composer handle.

This function returns an empty string if the composer type was not defined or if the search path does not contain an associated composer.