No pf dynamic marking in dynamic-scripts-init.ly

[Nick Payne]

I've been setting some Carcassi studies. His Op60 No 8 has a "pf" 
dynamic marking at one point (see 
http://erato.uvt.nl/files/imglnks/usimg/c/c8/IMSLP34430-PMLP03629-ribs0980_06.pdf, 
fifth stave on the first page), which does not exist in Lilypond. I 
added the variable definition pf = #(make-dynamic-script "pf") to my ly 
source, but is there any reason why this should not be added to 
dynamic-scripts-init.ly? That already contains fp as a dynamic marking, 
why not pf?

Nick