Examples:

XSPEC> setp c LA OT Testing     ! PLT label command

XSPEC> setp c LWidth 5          ! PLT line-width command

XSPEC> setplot lis              ! List the PLT command stack.

  1: LAbel OT Testing
  2: LWidth 5

XSPEC> setplot del 1            ! Delete the first command in the stack.

XSPEC> setplot lis

 1: LWidth 5