World of Origin's Age of Renewal
a) The Adept and the Divine Bard are the only caster classes available at first level to PCs.
b) The Bard class from the PHB is not available. Instead it is replaced with the Divine Bard Variant from Unearthed Arcana.
This Variant can also be found in the SRD:
c) This represents the fact that Bards are almost exclusively minstrels who travel the land singing of the exploits, merits, or outright awe of their patroned deity.
d) The Divine Bard must display his deity’s holy symbol while performing to be able to use her magical abilities.