These shell scripts invoke ed on .ch files to change change files.

The first line of a change block must start with @x <theme>. All
lines of a deactivated change block must start with a tab, i.e.
"shifted right."

Under these preconditions, e.g. the script mkinitex deactivates the block
marked by @x initex and the script mkprodtex activates the same
block.

The mk* scripts print the changed lines.

Some ch.ch files, like mkchatty, take one optional parameter.
"mkchatty" or "mkchatty tex" change tex.ch and "mkchatty mf" changes mf.ch.

These commands are idempotent. Applying twice a change script has
the same effect as applying it once.

Cf. section 11 of webman.tex for the format of change files.