OGC specifications
WMS
http://www.opengeospatial.org/standards/wms
WMTS
http://www.opengeospatial.org/standards/wmts
The OGC specification WMTS 1.0.0 sets that prebuilt data should be served where scales have been restricted to a discrete set of tiles that follows a regular grid geometry.
Provides a syntax (RESTful) that directs to a tile from a URL resulting from the combination of three indexes: zoom level, row and column of the tiles space.
http://mapcache.icc.cat/map/bases/wmts/1.0.0//{Layer}/{TileMatrixSet}/{TileMatrix}/{TileCol}/{TileRow}.{Format}
TileMatrixSet is the name of the grid, TileMatrix is the zoom level, TileCol and TileRow are the tile x and y.
Example: http://mapproxyd/map/bases/wmts/topo/UTM25831/1/0/1.jpeg
This syntax makes more efficient the Internet cache mechanisms as coordinates are not involved (with its possible rounding problems) and have a single identification of a tile.
WMTS specification also provides a KVP type syntax where no single identification of a tile exists, which makes the cache mechanisms less efficient.
The ICGC WMTS service follows the WMTS-REST syntax.
WCS
http://www.opengeospatial.org/standards/wcs
WFS
http://www.opengeospatial.org/standards/wfs