i don't know exactly what you mean, but try this one
set %txt $mid($1-, 1, 300)
set %txt1 $mid($1-, 300,
340)
set %txt2 $mid($1-, 640, 960)
etc...
set %txt1 $mid($1-, 300, 340) <== why 340? because 300 add 340 equal 640
hope i can help you with it, if not, please explain it what you're doing to do with
