### 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 enabled as follows:

          ./configure --enable-backwards-compatibility

Notice: Deprecated syntax items may be removed entirely 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