Manual:$wgUseXVO

HTTP proxy (CDN) settings: $wgUseXVO
Send X-Vary-Options header for better caching (requires patched Squid).
Introduced in version:1.16.0 (r53725)
Removed in version:1.27.0 (Gerrit change 243895; git #7e20cb51)
Allowed values:(boolean)
Default value:false

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Send X-Vary-Options header for better caching (requires patched Squid).