When you are done use UPDATE to add your macro to the dictionary and try it out. The output should look similar to this:
nM> contlab2 reg reg
REG.CONTLAB2=M: CONTLAB2,TAB=reg,PREFIX=reg
REG.SHELL=nxm.sys.lib.Shell@fd66a5
REG.HANDLERS.FILE.TMP=nxm.sys.lib.DataFile
REG.HANDLERS.FILE.RAW=nxm.sys.lib.BaseFile
REG.HANDLERS.FILE.PRM=nxm.sys.lib.DataFile
...
REG.HANDLERS.FILE.TOC=nxm.map.lib.TocFile
REG.HANDLERS.FILE.SID=nxm.map.lib.MrSidFile
REG.HANDLERS.PACKET.SDDS=nxm.sys.lib.SDDSPacket
REG.HANDLERS.PACKET.ICE=nxm.ice.lib.ICEPacket
REG.HANDLERS.RESOURCE.RAMD=nxm.ice.lib.RamDiskResource
REG.HANDLERS.RESOURCE.XMPIPE=nxm.sys.libxm.XmPipeResource