Read ECMA-48¹, which is the free (as in beer) printing of the ‘ANSI’ terminal controls standard. If you want to supply text (like a file name), you'd probably use an OSC command ESC ] Ps ; Pt ST with a Ps that no one else is using. To mark the start and end of a region, you'd probably use a pair of control sequences (CSI) analogous to START / END OF SELECTED AREA, from a private use range.
(The true-color sequence comes from an ITU recommended extension / future version, T.416². It would be interesting for the OP site to list which terminals support the full proposal, including CMY an CMYK specifications, as well as RGB.)
(The true-color sequence comes from an ITU recommended extension / future version, T.416². It would be interesting for the OP site to list which terminals support the full proposal, including CMY an CMYK specifications, as well as RGB.)
¹ http://www.ecma-international.org/publications/files/ECMA-ST... ² http://handle.itu.int/11.1002/1000/2546-en?locatt=format:pdf