Repeat blocks in Commands

A “repeat block” is a fixed chunk of keywords that can be applied to all keywords one level above it. The repeat block is used to present the chunk of keywords once on the command reference page, rather than repeating the block (hence the name) after every keyword above it.

Construct as follows.

1. In the body of the main command reference, the keyword block is denoted in square brackets ([ ]) by a unique name, specified at the appropriate location, within a keyword signature:

   .. kwd:: Velocity [zonefieldoptions]
   

2. Below the main body of the command, the block is presented. The section starts with a .. rubric::

   .. rubric:: Optional Block Apply Modifiers
      :class: h2
      :name: zonefieldoptions
   

   Here, most importantly, the :name: argument of the directive must exactly match the unique name supplied in the preceding keywords.

3. A description of the content of the block follows:

   The following modifiers are available to specify additional information for the geometry paint-extra keywords. The following keywords are available.

4. A list of keywords then follows. Each keyword must be given the argument :class: rblock

   .. kwd:: XDX
      :class: rblock
   
      Get the *x*-component of the vector.
   

End of explanation for now.