Source Cache
From EMule Wiki
If we have received more sources from a source exchange than the hardlimit can handle, the extra sources are not thrown away but stored in a Source cache and extracted from that in case there are sources lost from a file. This saves some extra reasks for SX from peers.
The extra sources in the cache are thrown away after some time.
[edit] See also
Idea from xman(?), implemented in Xtreme, Neomule, StulleMule, MorphXT.