Half a tithi is a karana, so there are sixty in a lunar month. But there are only eleven kinds, and four of those appear exactly once each.

Seven karanas rotate round and round through the month, and four fixed ones are pinned to the turn between the old moon and the new. The four rare ones carry the ominous names — Shakuni, Chatushpada, Naga, Kimstughna — and land in the last hours of the waning moon and the first of the waxing, which is the part of the cycle almost every tradition treats warily.