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4. 2021
5. February 2021

Today the minimum version of VCL available across our network increased, unlocking the following changes:

Improved content

• We've renamed a bunch of function arguments in places where names were previously misleading; for example, arguments referred to as pattern despite not being regular expressions. These are now more correctly referred to as subject or target.
• Historically, we have used the word 'datacenter' to refer interchangeably to either a physical location at which Fastly has a presence, or to a set of Fastly servers acting together as a cache. These concepts are no longer always the same, and so references to 'data center' have been changed to reflect whether they, in each case, refer to a site or to a POP.
• We better described the behavior of not set values when assigned to STRING variables.
• The client.sess_timeout variable's default value was corrected: the reference incorrectly stated that this was 10 seconds when it is actually 10 minutes.

Updated function and variable descriptions

We expanded the descriptions of a number of functions and variables, adding detail, code examples, and, in some cases, better explanations of error conditions or edge cases. There were updates to:

• obj.ttl
• req.body
• client.geo.ip_override
• beresp.ttl
• xml_escape
• table.lookup
• subfield
• std.suffixof
• std.strlen
• std.replaceall
• std.replace
• std.replace_suffix
• std.replace_prefix
• geoip.city