I've installed Tex Live 2010 on a mac, and when trying to use xelatex, I get the error:
!Latex Error: File `expl3.sty' not found
What is this package, and how can I get it installed on tex live? There are no updates available, according to the Tex Live utility.
Update: I've found the 'tlmgr' utility, and done: sudo tlmgr install expl3
So far, so good. Unfortunately, I am now told I need xparse.sty. xparse.sty is not available through tlmgr ("package xparse not present in package repository").
Needless to say, I am not using xparse directly, nor am I directly using calc.sty, which is the file that was mentioned just before this error.
Further update: xparse is obtained by installing 'xpackages'.