Dunno if this belongs in "Blame the Manual" but cant see where else it fits.

Is the "file_str_writeto" function in experimental stage or something?
Its listed in the manual with "file_str_write" and there is no mention of experimental there.
And if I include it in my code I get "undeclared identifier" errors.
And I cant find any reference to it in "Bugs".
[PS:: Im running 7.80.0 commercial]

So whats the go guys ....?
Thx.