Hi, Readline currently uses SOH (\001) and STX (\002) to label parts of the text that does not use up screen space, but from the documentation point of view it is hidden behind the C macros `RL_PROMPT_START_IGNORE' and `RL_PROMPT_END_IGNORE'. This makes the documentation inaccessible to people using readline from other languages (including bash PS1 via command substitution), unless the binding explicitly provides these constants.
I propose putting the values of the two definitions explicitly in the readline documentation.for rl_expand_prompt. It is already partially present in the user-interface documentation about the mode strings. There shouldn't be any compatibility issues, as a change would require the invoking program to be recompiled anyways. Thanks, Mingye Wang (Artoria2e5)
