why ed? 3270 terminal emulator is line based.
Here is some stuff to get basic work done
symbols
* . current line
* $ last line
* n nth line fro 0 to $
* - previous line
* ^n nth previous line
* + next line
* +n nth next line
* , all lines 1 to $
* ; current to last . to $
command mode
* q quit
* Q quit no save
* u undo command
* w save (can specify new file name)
* [.,.]d delete lines or current line
* [.,.]c change lines or current line
* [.,.]j join lines or current line
* i insert before current line
* [.,.]m move lines or current line to current
* [.,.]t copy lines or current line to current
* [.,.]n print lines or current line with line numbers
* [.,.]p print lines or current line
* [.,.]l print lines or current line wait for neeline at end of page (don't do this w/ big files!)
* /text search for text
Example .,+32n print 32 lines from current
edit mode
* . leave