Official; Crown Copyright 2014; Released under OGL XML Schema Maintenance Debbie Wilson, Peter Parslow Geographic Information Architects May 2014

INSPIRE GML Encoding MIWP-18 XML schema maintenance Suggestion at gml-encoding/wikihttps://ies-svn.jrc.ec.europa.eu/projects/inspire- gml-encoding/wiki Based on OGC schema version numbering MAJOR.MINOR.PATCH All versions persist Note: this is namespace versioning (not.xsd file versioning) MAJOR version when you make incompatible changes, MINOR version when you add functionality in a backwards- compatible manner, and PATCH version when you make backwards-compatible bug fixes. Official; Crown Copyright 2014; Released under OGL

Definitions Patch: A bug fix is defined as an internal change that fixes incorrect behaviour – no new functionality Some ‘bug fixes’ may be major changes! E.g. correcting a wrongly spelled element name Minor: backwards compatible – new optional things Major: ‘backwards incompatible’ “Breaking change” – new mandatory things; or things removed Backwards Compatibility: Data is compatible with earlier versions of the schema or is it the other way round – old data is compatible with the new schema? Official; Crown Copyright 2014; Released under OGL

A.1 Examples of major version increments¶ The following are typical examples which require a major version increment to be applied: Name of a feature, attribute or association role is changed. A feature, attribute or association role is deleted. Add a new attribute or association role with multiplicity of 1 or 1..* Changing the multiplicity of an attribute or association role from 0..1 or 0..* to 1 or 1..* Change or delete an existing enumerated value Changing the sequence order of attributes and association roles in the schema Change an attribute to make it voidable (i.e. nullable) Changing the type of an attribute which requires transformation (e.g. string to DateType). Note if the change to type does not require transformation then this could be treated as a minor change. Changing the coordinate reference system of the dataset or feature type Official; Crown Copyright 2014; Released under OGL

Example of a major (breaking) bug fix ProtectedSites 3.0: Official; Crown Copyright 2014; Released under OGL Should be

A.2 Examples of minor version increments¶ The following are typical examples which require a minor version increment to be applied: A new feature Add a new attribute or association role with multiplicity of 0..1 or 0..* Alter the multiplicity of an attribute or association role from 0..1 to 0..* Alter the multiplicity of an attribute or association role from 1 to 1..* Add a new value to an enumeration Change a type to xml:string Official; Crown Copyright 2014; Released under OGL

Questions What does a “Breaking change” break? Data production Data consumption Some software hard codes styling from enumeration values Deprecating functionality Should this always be handled with a minor, and then a major to remove it? How much notice to give? To data publishers – compliance requirement To data consumers To software vendors Official; Crown Copyright 2014; Released under OGL

Links for further information OGL: Open Government LicenceOpen Government Licence OGC Policy Directives for Writing and Publishing OGC Standards ( r11):