Jacob's thigh was disabled by the Angel, to show the patriarch that his prevalence was through his faith and prayer, not through force, Genesis 32:25-31. Smiting the thigh was a gesture of self-condemnation and grief, Jeremiah 31:19 Ezekiel 21:12.
In general, a datum is a base elevation used as a reference from which to reckon heights or depths. A tidal datum is a standard elevation defined by a certain phase of the tide.
A checksum is a small-size datum from a block of digital data for the purpose of detecting errors which may have been introduced during its transmission or storage. It is usually applied to an installation file after it is received from the download server.