The use of upper and lower case in the abbreviation dGBe is one way of indicating which octave the strings are in, the upper-case octave being lower in pitch than the lower-case octave ... it's not supposed to make sense !!
Ergo this description indicates a high (re-entrant) d string, where the other three strings are "normal" baritone tuning (the same as the three treble strings on a guitar). The octave changes definition on the C, so if one was to expand this, the two octaves would look like : CDEFGABcdefgab , there are other means of indicating the octaves above and below these two, but this'll do for now
The picking and strumming patterns will now be similar to those used on a gCea (conventional) re-entrant ukulele, especially for claw-hammer and campanella-style playing, though obviously everything will be five semi-tones lower.
As to what strings ... a set of standard baritone strings with the bass string replaced by an extra E string tuned down two semitones should do the job
Thank you, Kypfer. Now I understand. It's just another way of denoting a high d baritone tuning, a tuning well-liked by many baritone players, a tuning I already use on one of my baritones. The small just indicates the octave.