I'm trying to get my head around the theoretical side of XML and GML. The OGC web page for GML states that:
The Geography Markup Language (GML) is an XML grammar for expressing geographical features.
But what does it mean by a "grammar"? I can't see that phrase (as a noun) used anywhere else. Is it a unique GML meaning?
I see the terms "language", "schema", "format" and "standard". Are they the same thing?
So can I say that GML is an XML schema? Or would that mean something different? If so, is there a single XSD file that defines the entire GML specification?