pls help me grok ELF, basis of PCA

So this PCA stuff
	http://www.cs.princeton.edu/sip/projects/pca/

is based on this ELF thing
	http://www.dcs.ed.ac.uk/lfcsreps/91/ECS-LFCS-91-162/

So I'm trying to read the ELF paper. I can't parse the formulas.
In partuclar, the B-KIND-SIG rule on page 7... second premise.
It seems to say

	K is a kind in \sigma

but this doesn't match any of the assertion forms on the previous page:

	\sigma is a valid signature
	\gamma is a valid context in \sigma
	K is a kind in \gamma and \sigma
	A has kind K in \gamma and \sigma
	M has type A in \gamma and \sigma

Help? Do they imply an empty \gamma in their notation or something?

-- 
Dan Connolly, W3C http://www.w3.org/People/Connolly/