In the fitting mode, single and double quotes serve to indicate that all the characters between quotes should be taken as only one word, even if there are some blanks (tab or space) among them. The difference between single and double quotes is that within the former variable expansion (using `$') does not take place whereas it does in the latter. Quotes are not recognized between parentheses.
In C-calculator mode, double quotes serve to indicate a string and
parsing is done accordingly. As in C, double quotes can be included in
a string using the `\
' operator. Note that C special characters
as '\n
' for a newline, '\a
' for a bell, '\t
' for
a tab, and so on, are recognized in a string. Single quotes have no
special meanings. The only way to pass a `$' without expanding the
following name is to escape the `$' with a `\
'.
Thus, a null string is given by '' or "" in the fitting mode and by "" only in C-calculator mode.
In pmode, both single and double quotes are freely passed to the
plotting program. This is valid when trailing commands are are passed
to pmode, although implicitly stays in the fitting
mode. Once again, expansion of a `$' followed by a string can be
avoided using the escape character, i.e., by typing `\
$'.
exec, set plotting, math function scan, print