Return to tt13 CVS log

Up to [CSRG BSD Unix] / 43BSDReno / share / doc / usd / 25.trofftut

Annotation of 43BSDReno/share/doc/usd/25.trofftut/tt13, revision 1.1.1.1

1.1       root        1: .\"    @(#)tt13        6.1 (Berkeley) 5/23/86
                      2: .\"
                      3: .NH
                      4: Environments
                      5: .PP
                      6: As we mentioned, there is a potential problem
                      7: when going across a page boundary:
                      8: parameters like size and font
                      9: for a page title may well be different from those
                     10: in effect in the text when the page boundary occurs.
                     11: .UL troff
                     12: provides a very general way to deal with this and
                     13: similar situations.
                     14: There are three `environments',
                     15: each of which has independently settable versions of
                     16: many of the parameters associated with processing,
                     17: including size, font, line and title lengths,
                     18: fill/nofill mode, tab stops, and even partially collected lines.
                     19: Thus the titling problem may be readily solved by processing the main text
                     20: in one environment and titles in a separate one
                     21: with its own suitable parameters.
                     22: .PP
                     23: The command
                     24: .BD .ev\ n
                     25: shifts to environment
                     26: .BD n ;
                     27: .BD n
                     28: must be 0, 1 or 2.
                     29: The command
                     30: .BD .ev
                     31: with no argument returns to the
                     32: previous environment.
                     33: Environment names are maintained in a stack, so calls
                     34: for different environments may be nested and unwound consistently.
                     35: .PP
                     36: Suppose we say that the main text is processed in environment 0,
                     37: which is where 
                     38: .UL troff
                     39: begins by default.
                     40: Then we can modify the new page macro
                     41: .BD .NP
                     42: to process titles in environment 1 like this:
                     43: .P1 2
                     44: ^de NP
                     45: ^ev 1  \e" shift to new environment
                     46: ^lt 6i \e" set parameters here
                     47: ^ft R
                     48: ^ps 10
                     49: \&... any other processing ...
                     50: ^ev    \e" return to previous environment
                     51: ^^
                     52: .P2
                     53: It is also possible to initialize the parameters for an environment
                     54: outside the
                     55: .BD .NP
                     56: macro,
                     57: but the version shown keeps all the processing in one place
                     58: and is thus easier to understand and change.

This archive runs on limited infrastructure. Preserving old code on modern bandwidth. Automated agents are requested to crawl responsibly.