Proposal
For Pass8 GlastRelease will need access to all the irfs packages. Rather than adding these packages in the usual way, the proposal has been made to put them in their own external and put all the packages they depend on (facilities, astro, etc.) in another external. ST and GR would then link to both of these externals. GRBAnalysis could also.
Alternative #1
Put all of the above in a single external. ST, GR and GRBAnalysis all need all of these things.
Pro: would simplify bookkeeping somewhat
Con: irfs could be much more volatile than the other packages
Alternative #2
Put all of the above plus other common packages (celestialSources, flux, xmlBase) into a single new external.