Run Length Encoding is one way to send pictures over the telephone lines. Picture data replaces character data. The parity bit is ignored, as are ASCII control codes except 07h.
The divider bar shows where there are too many PAPER pixels to fit in a byte. An INK byte for 0 pixels is inserted. Any number of pixels can be accommodated. In this way, bytes alternate between INK and PAPER. 32 is added to pixel count so that 0 to 95 pixels can be stuffed in each byte. The list of bytes is ended by 07h. It begins after a header ending in “GH”. Headers can be up to 101 bytes.
Picture data above is:…/127/32/44/33/34 37/33/39/34/34/55/45/34/38/33/33/37/33/33 35/47/51/35/35/33/36/34/39/34/38/34/37/35 36/38/33/34/39/33/36/33/39/37/33/42/…
RLE works best with line drawings. It often yields files bigger than SCREEN$, so file compression is not to be expected.
BBS Uploading and downloading is its forte, at which it excels.