I had posed the 4 characters problem on the forum at SQUARP: http://squarp.community/t/cc-definition-display-the-wrong-label/917/5?u=bricefa33
Their response doesn’t leave much hope.
I still made a definition file with 4 characters for GM drum map in my Kurzweil PC3 :
NAME:PC3 DRGM
OUT:A
CHANNEL:10
N27:HQ
N28:SLAP
N29:SCPH
N30:SCPL
N31:STIC
N32:SQCL
N33:METC
N34:METB
N35:ACBD
N36:BD1
N37:SSTIC
N38:ACSN
N39:CLAP
N40:ELSN
N41:LFTM
N42:CLHH
N43:HFTM
N44:PDHH
N45:LOTM
N46:OPHH
N47:LMTM
N48:HMTM
N49:CRCY
N50:HITM
N51:RICY
N52:CHCY
N53:RICY
N54:TAMB
N55:SPCY
N56:COWB
N57:CRCY
N58:VIBS
N59:RICY
N60:HBGO
N61:LBGO
N62:MHGA
N63:OHGA
N64:LOGA
N65:HTIM
N66:LTIM
N67:HOGO
N68:LOGO
N69:CABA
N70:MARA
N71:SWHI
N72:LWHI
N73:SGUI
N74:LGUI
N75:CLAV
N76:HBLO
N77:LBLO
N78:MCUI
N79:OCUI
N80:MTRI
N81:OTRI
N82:SHAK
N83:JBEL
N84:BELT
N85:CAST
N86:MSUR
N87:OSUR
N88:APPL
some are clear others not 