1.5 Backwards compatibility

Gnuplot version 4.0 deprecated certain syntax used in earlier versions, but continued to recognize it. This is now under the control of a configuration option, and can be disabled as follows:

      ./configure --disable-backwards-compatibility

Notice: Deprecated syntax items may be disabled permanently in some future version of gnuplot.

One major difference is the introduction of keywords to disambiguate complex commands, particularly commands containing string variables. A notable issue was the use of bare numbers to specify offsets, line and point types. Illustrative examples:

Deprecated:

      set title "Old" 0,-1
      set data linespoints
      plot 1 2 4               # horizontal line at y=1

New:

      TITLE = "New"
      set title TITLE offset char 0, char -1
      set style data linespoints
      plot 1 linetype 2 pointtype 4