REST query request: Can I use $etag parameter?

X3 REST API includes $etag and $uuid parameters in query response:
{
"$itemsPerPage": 20,
"$resources": [
{
"$uuid": "454eef01-bf0b-8344-bade-483f44265ffd",
"$etag": "2017-04-24T19:46:25Z",
"NUM": "FR0110304FACLI000001",
"INVTYP": 1,
"INVDAT": "2017-04-24",
"INVREF": "Test 21",
"INVSTA": 1,
"BPCINV": "FR004",
"SALFCY": "FR011",
"SALFCY_REF": {
"$title": "Comptech",
"$description": "Comptech SA"
}
}
],
"$links": {
"$last": {
"$url": "sagex3v9:8124/.../SINVOICEV
"$type": "application/json;vnd.sage=syracuse",
"$method": "GET"
}
}
}

$etag value seems to be last modified date of the object.
Can I use it in a REST query to get list of objects modified since certain date?

When I tried to include $etag in where as a regular field
http://sagex3v9:8124/api1/x3/erp/SEED/SINVOICEV?representation=EDISIHEM.$query&where=$etag gt @2017-01-01@
I received "no label" error.

I know that I can modify the representation and include CREADATTIM field for using in query but I'd like first to make sure that there is no way
to use $etag.