ESI
- beresp.do_esi —Whether to enable ESI on the fetched object
- esi.allow_inside_cdata —Whether to enable ESI directives inside CDATA blocks
- req.esi —Whether to enable ESI processing during a request
- req.esi_level —Level of ESI subrequest
- req.is_esi_subreq —Whether VCL is being evaluated within an ESI fragment
- req.topurl —For an ESI-generated request, the URL of the original request
