NGX_HTTP_IMS_OFF 147 src/http/modules/ngx_http_not_modified_filter_module.c if (clcf->if_modified_since == NGX_HTTP_IMS_OFF) { NGX_HTTP_IMS_OFF 124 src/http/ngx_http_core_module.c { ngx_string("off"), NGX_HTTP_IMS_OFF },