## 1.52.30 label

    set label <label number> <text>
      [ <system> ] <x>, [ <system> ] <y>, [ [ <system> ] <z> ]
      [ rotate <angle> ]
      [ with { ( color <color> | fontsize <size> ) } ]

where `<system>` may take any of the values
`( first | second | screen | graph | axis<number> )`

The `set label` command is used to place text labels on graphs. The example

    set label 1 'Hello' 0, 0

would place a label reading ‘Hello’ at the point on a graph, as measured along the `x`- and `y`-axes. The tag `1` immediately following the keyword `label` is an identification number and allows the label to be subsequently removed using the `unset label` command. By default, the positional coordinates of the label are specified relative to the first horizontal and vertical axes, but they can alternatively be specified in any one of several coordinate systems. The coordinate system to be used is specified as in the example:

    set label 1 'Hello' first 0, second 0

The name of the coordinate system to be used precedes the position value in that system. The coordinate system `first`, the default, measures the graph using the `x`- and `y`-axes. `second` uses the `x2`- and `y2`-axes. `screen` and `graph` both measure in centimeters from the origin of the graph. The syntax `axis<n>` may also be used, to use the th horizontal or vertical axis; for example, `axis3`:

    set label 1 'Hello' axis3 1, axis4 1

A rotation angle may optionally be specified after the keyword `rotate` to produce text rotated to any arbitrary angle, measured in degrees counter-clockwise. The following example would produce upward-running text:

    set label 1 'Hello' 1.2, 2.5 rotate 90

By default the labels are black; however, an arbitrary color may be specified using the `with color` modifier. For example,

    set label 3 'A purple label' 0, 0 with color purple

would place a purple label at the origin.