2.11.2 Enabling MBSTRING to be Self-describing
MBSTRING can be self-describing if
sendlen is set to zero. Some Tuxedo buffers provide a
capability for the buffer to determine its own length if the user
does not provide it. This self-describing behavior is triggered
when an application sets the sendlen argument of a
Tuxedo function call (for example, tpcall()) to
zero.