Because I keep forgetting these and having to check:
Ensembl co-ords are 1-based, fully closed: The range [1,5] means positions 1,2,3,4,5.
UCSC data co-ords are 0-based, half-open: The range [0,5) means positions 1,2,3,4,5
Confusingly, their genome browser uses 1-based, fully closed (ie they add 1 to the internally stored start (but not end) position of any interval before displaying it in the browser).
Also see this useful biostar cheatsheet: http://www.biostars.org/p/84686/