!Code to declare x and give x a value.
A logical variable can take one of two states representing true and false.
These are represented in programs by:
with full stops at the beginning and the end.
For input and output, the edit descriptor Lw is used with logical
variables. w is the field width. The output is the letter T (for true)
or F (for false), padded with leading spaces. On input only the first character
(after optional leading spaces and an optional full stop) is significant. This
must be either the letter T or the letter F.