Editing Geography Markup Language (section)

===Profile===

'''GML profiles''' are logical restrictions to GML, and may be expressed by a document, an [[XML Schema (W3C)|XML schema]] or both.  These profiles are intended to simplify adoption of GML, to facilitate rapid adoption of the standard. The following ''profiles'', as defined by the GML specification, have been published or proposed for public use:

* A ''[[#Point Profile|Point Profile]]'' for applications with point geometric data but without the need for the full GML grammar;
* A ''[[#GML Simple Features Profile|GML Simple Features profile]]'' supporting vector feature requests and transactions, e.g. with a [[Web Feature Service|WFS]];
* A GML profile for [[Jpeg2000#GML JP2 georeferencing|GMLJP2]] (GML in JPEG 2000);
* A GML profile for [[RSS]].

''Profiles'' are distinct from [[#Application schema|application schemas]]. ''Profiles'' are part of GML [[namespace]]s (Open GIS GML) and define restricted subsets of GML.  Application schemas are XML vocabularies defined using GML and which live in an application-defined target namespace. Application schemas can be built on specific GML profiles or use the full GML schema set.

Profiles are often created in support for GML derived languages (see [[#Application schema|application schemas]]) created in support of particular application domains such as commercial aviation, nautical charting or resource exploitation.

The GML Specification (Since GML v3.) contains a pair of [[XSLT]] scripts (usually referred to as the "subset tool") that can be used to construct GML profiles.

====GML Simple Features Profile====

The ''GML Simple Features Profile'' is a more complete profile of GML than the above ''Point Profile'' and supports a wide range of vector feature objects, including the following:

# A reduced geometry model allowing 0d, 1d and 2d linear geometric objects (all based on linear interpolation) and the corresponding aggregate geometries (gml:MultiPoint, gml:MultiCurve, etc.).
# A simplified feature model which can only be one level deep (in the general GML model, arbitrary nesting of features and feature properties is not permitted).
# All non-geometric properties must be XML Schema simple types – i.e. cannot contain nested elements.
# Remote property value references (xlink:href) just like in the main GML specification.

Since the profile aims to provide a simple entry point, it does not provide support for the following:
* coverages
* topology
* observations
* value objects (for real time sensor data)
* dynamic features

Nonetheless it supports a good variety of real world problems.

====Subset tool====

In addition, the GML specification provides a ''subset tool'' to generate GML profiles containing a user-specified list of components. The tool consists of three XSLT scripts. The scripts generate a profile that a developer may extend manually or otherwise enhance through schema restriction. As restrictions of the full GML specification, application schemas that a profile can generate must themselves be valid GML application schemas.

The subset tool can generate profiles for many other reasons as well. Listing the elements and attributes to include in the resultant profile schema and running the tool results in a single profile schema file containing only the user-specified items and all of the element, attribute and type declarations on which the specified items depend. Some Profile schemas created in this manner support other specifications including [[IHO]] [[IHO#Publications|S-57]] and GML in JPEG 2000.