This function returns 1 (True) if the tag specified by tagname has an attribute declared as #CONREF in the DTD. If the tag doesn't have this attribute, the function returns 0. If the DTD for your document includes the NAMECASE GENERAL NO specification, then the tagname parameter will be case sensitive. (If you have applied an alias map to the document, tagname can be either an alias or a real name.)

The doc argument specifies the identifier of the document tree. If doc is omitted or 0, the current document is used.