Creating markup macros

[Paul Scott]

I'm trying to learn to create markup (and other) macros.  This is my 
current code to simply produce \markup{ \number 1 }.  I want it 
eventually to use numerator and denominator to work for the current 
meter.  Can someone give me some hints as to what this simple version is 
missing or documentation I may not have found yet?  I have read "8.2 
Markup programmer interface" and the Scheme Tutorial.

#(def-markup-command (restOne layout props)
 (interpret-markup layout props
  (markup #:number #1)))

rOne = { R1^\restOne }

\score{ \rOne }

TIA,

Paul Scott