5.23.56 xrange

set x[<axisnumber>]range '<text>'

The xrange setting controls the range of values along the $x$-axes of plots. For function plots, this is also the domain across which the function will be evaluated. For example:

set xrange [0:10]

sets the first $x$ axis to be between 0 and 10. Higher numbered axes may be referred to be inserting their number after the $x$; $y$-axes similarly be replacing the $x$ with a $y$. Hence:

set y23range [-5:5]

sets the range of the 23rd $y$-axis to be between -5 and 5. The following command:

set xrange [:10]

would set the $x$-axis to have an upper limit of 10, but an automatically-scaling lower-limit.