On Monday, at 12:59, Jack O'Quin wrote:
| (My apologies: this discussion is more appropriate for answers.ros.org
| than for the entire ros-users list.)

Sorry about that.

So, just to wrap up for the records some off-list discussions and rephrase my
initial question:

Q: Is it possible to define positional-only parameters in services?
A: No, you cannot. Service parameters must be named.