Additionally, gnuplot may define some variables under various operations.
Working with interactive terminals with mouse functionality defines variables with names that begin "MOUSE_", see mouse variables (p. ) for details.
Further, there are several "read-only" variables that begin "GPVAL_", like GPVAL_TERM, GPVAL_X_MIN, GPVAL_X_MAX, GPVAL_Y_MIN,... Type show variables all to display their list and values. Values related to axes parameters (ranges, log base) are values used during the last plot, not those currently set.
The fit mechanism uses several variables with names that begin "FIT_". It is safest to avoid using such names. "FIT_LIMIT", however, is one that you may wish to redefine. Under set fit errorvariables, the error for each fitted parameter will be stored in a variable named like the parameter, but with "_err" appended. See the documentation on fit (p. ) for details.
See user-defined variables (p. ), mouse variables (p. ), and fit (p. ).