if_modified_since

This directive appeared in version 0.7.24.

Specifies how to compare modification time of a response with the time in the “If-Modified-Since” request header field:

off

the “If-Modified-Since” request header field is ignored (0.7.34);

exact

exact match;

before

modification time of a response is less than or equal to the time in the “If-Modified-Since” request header field.