Extracted from "The XA specification, chapter 5, page 26":
"A resource manager must call this function from the same thread of control from
which the application accesses the resource manager. A resource manager taking
advantage of this facility must have TMREGISTER set in the flags element of its
xa_switch_t structure (see Chapter 4). Moreover, ax_reg() returns failure,
[TMER_TMERR], when issued by a resource manager that has not set TMREGISTER."
Current LIXA implementation does not check TMREGISTER flag.