Summarize the interpretation of + and - with the various data types in "Upgrading to 5.1".
Summarize the interpretation of + and - with the various data types
in "Upgrading to 5.1".

Also make an optimistic statement about the compatibility of VCL
written for 5.0 with 5.1.

feld/Varnish-Cache,gquintard/Varnish-Cache,feld/Varnish-Cache,feld/Varnish-Cache,gquintard/Varnish-Cache,feld/Varnish-Cache,feld/Varnish-Cache,gquintard/Varnish-Cache,gquintard/Varnish-Cache