Changing the Vertical Spacing (The GNU Troff Manual)

#### 5.20.2 Changing the Vertical Spacing

Request: `.vs` [space] ¶
Request: `.vs` `+`space ¶
Request: `.vs` `-`space ¶
Register: `\n[.v]` ¶

  Set the vertical spacing to, or alter it by, space. The default scaling unit is ‘`p`’. If `vs` is called without an argument, the vertical spacing is reset to the previous value before the last call to `vs`. GNU `troff` emits a warning in category ‘`range`’ if space is negative; the vertical spacing is then set to the smallest possible positive value, the vertical motion quantum (as found in the `.V` register).

  ‘`.vs 0`’ isn’t saved in a diversion since it doesn’t result in a vertical motion. You must explicitly issue this request before interpolating the diversion.

  The read-only register `.v` contains the vertical spacing; it is associated with the environment (see Environments).

When a break occurs, GNU `troff` performs the following procedure.

- Move the drawing position vertically by the extra pre-vertical line space, the minimum of all negative `\x` escape sequence arguments in the pending output line.
- Move the drawing position vertically by the vertical line spacing.
- Write out the pending output line.
- Move the drawing position vertically by the extra post-vertical line space, the maximum of all positive `\x` escape sequence arguments in the line that has just been output.
- Move the drawing position vertically by the post-vertical line spacing (see below).

Prefer `vs` or `pvs` over `ls` to produce double-spaced documents. `vs` and `pvs` have finer granularity than `ls`; moreover, some preprocessors assume single spacing. See Manipulating Spacing, regarding the `\x` escape sequence and the `ls` request.

Request: `.pvs` [space] ¶
Request: `.pvs` `+`space ¶
Request: `.pvs` `-`space ¶
Register: `\n[.pvs]` ¶

  Set the post-vertical spacing to, or alter it by, space. The default scaling unit is ‘`p`’. If `pvs` is called without an argument, the post-vertical spacing is reset to the previous value before the last call to `pvs`. GNU `troff` emits a warning in category ‘`range`’ if space is negative; the post-vertical spacing is then set to zero.

  The read-only register `.pvs` contains the post-vertical spacing; it is associated with the environment (see Environments).