As we mentioned, there is a potential problem
when going across a page boundary:
parameters like size and font
for a page title may well be different from those
in effect in the text when the page boundary occurs.
provides a very general way to deal with this and
There are three `environments',
each of which has independently settable versions of
many of the parameters associated with processing,
including size, font, line and title lengths,
fill/nofill mode, tab stops, and even partially collected lines.
Thus the titling problem may be readily solved by processing the main text
in one environment and titles in a separate one
with its own suitable parameters.
with no argument returns to the
Environment names are maintained in a stack, so calls
for different environments may be nested and unwound consistently.
Suppose we say that the main text is processed in environment 0,
Then we can modify the new page macro
to process titles in environment 1 like this:
^ev 1 \e" shift to new environment
^lt 6i \e" set parameters here
\&... any other processing ...
^ev \e" return to previous environment
It is also possible to initialize the parameters for an environment
but the version shown keeps all the processing in one place
and is thus easier to understand and change.