GML was developed with a number of explicit design goals, a few of which overlap the objectives of XML itself:
provide a means of encoding spatial information for both data transport and data storage, especially in a wide-area Internet context;
be sufficiently extensible to support a wide variety of spatial tasks, from portrayal to analysis;
establish the foundation for Internet GIS in an incremental and modular fashion;
allow for the efficient encoding of geo-spatial geometry (e.g. data compression);
provide easy-to-understand encodings of spatial information and spatial relationships, including those defined by the OGC Simple Features model;
be able to separate spatial and non-spatial content from data presentation ...