Plasmid nomenclature

[MUNGO at UVVM.UVIC.CA]

I have a rather simple question regarding the description of a plasmid as
presented in a paper.  The plasmid contains multiple genes that have been
spliced together and this is described in the paper as "CAB::LUC::E9".  I
know the CAB, LUC, and E9.  Is there any significance to the "::"?  Does
it have a specific meaning ?  Excuse the ignorance if this is common.
Mungo