Each request made contains metadata about the request in the header of the response. This information includes the URI, the string that was queried, the format requested and other information:

uriThe Unique Resource Identifier of this result.char1
queryThe query string, decoded.char1
formatThe requested format.char1
datasetThe datasets requested.char1
maxresultsThe maxresults requested.integer0..1
offsetThe offset requested.integer0..1
totalresultsThe total number of results found (may be more than returned).integer1
lrThe language requested.char0..1
epochA version reference for the Data product.char1
filterThe fq parameter(s) and their value(s) requested.char0..1
output_srsThe output spatial reference system.char1
srsThe projection the geospatial search coordinates are in. Only returned for Nearest, BBox and Radius resources.char0..1