We need to know what characters are invalid for Reuters symbol names so we can use one of them to map '/' which we use as a separator but can be a valid character in Reuters symbol names. From the rather old User Guide I have here it looks like ' ' is a candidate but I'd like to get the official line on this.
You can find further details on RIC code components in the Elektron Edge Programmers Guide
I also found another (internal) doc which states:
The following are not considered legitimate characters anywhere within RICs.