https://www.wikidata.org/w/api.php?action=wbparsevalue&datatype=time&values=1994-02Z
gives
{
"results": [
{
"raw": "1994-02Z",
"value": {
"time": "+1994-02-01T00:00:00Z",
"timezone": 0,
"before": 0,
"after": 0,
"precision": 11,
"calendarmodel": "http://www.wikidata.org/entity/Q1985727"
},
"type": "time"
}
]
}Per the definition in mw:Wikibase/DataModel the default values for month and day should be 00 and not 01. So instead of "time": "+1994-02-01T00:00:00Z", it should be "time": "+1994-02-00T00:00:00Z". Looks like the Z is triggering it, because https://www.wikidata.org/w/api.php?action=wbparsevalue&datatype=time&values=1994-02 does give the right result.