> According to POSIX specification semaphore name is not required to be
> started with slash character:

> "If name does not begin with the slash character, the effect is 
> implementation-defined."

Thus, POSIX indicates that if you want to guarantee the behavior, you
must use one (and only one) slash character at the start of the name.
Anything else is "implementation defined", and assuming that the documentation
indicates that lacking a leading slash leads to failure, the implementation
meets the requirement.