HP DCE/9000 Version 1.7 Application Development Tools for HP-UX 11.0 Release Note

HP DCE 1.7 Application Development Tools Release Note 43
Developing DCE Applications with HP DCE/ 9000
Notes on Programming with HP DCE
vfork()
The HP DCE Threads vfork() wrapper cannot be circumvented. The
methods used to circumvent other wrappers (defining
_CMA_NOWRAPPERS_, undefining vfork, defining vfork to be
_vfork_sys) do not work.