In this COBOL system, XML Extensions uses the standard COBOL calling convention. If your programs are also using the standard library routines implemented for RM/COBOL compatibility, you need to be aware that these are called using the 1024 calling convention.
Generally, you should explicitly use the 1024 calling convention when calling your RM/COBOL standard library routines, but if you are using the DEFAULTCALLS Compiler directive to set this calling convention, you will need to override it when calling to XML Extensions.