Items in the common package may be reused across different schemas. -- Name -- ESPAS Identifier -- Definition -- The identifier of the object in the ESPAS system -- Description -- Every standalone data object in the ESPAS system must have an ESPAS_Identifier defined. Guidelines for ESPAS_Identifiers: namespace shall uniquely identify the 'owner' of the item and shall be according to an agreed convention within the ESPAS system. e.g. stfc, nkua, eiscat, dlr etc. localID assignments are at the discrection of the'owner but shall be alphanumeric strings with no spaces, [a decision needs to be take as to we encourage the use of opaque or non-opaque identifiers e.g. ABC234 versus radarX] version numbers are at the discretion of the owner but should usually follow typical conventions 1, 2, 3 or 1.0, 1.1, 2.0 Both namespaces and localIds should be suitable for inclusion in URLs i.e. must not use the following reserved characters: = | ; | / | # | ? | : | space ---------------------------------------------------------- Encoding namespaces according to the guidelines will enable the publication of information resources in a RESTful manner. e..g (exact url structure to be agreed) http://www.espas-fp7.eu/dataset/stfc/STFC24/ (latest version of stfc owned object STFC24) http://www.espas-fp7.eu/dataset/stfc/STFC24/2 (version 2) or with non-opaque identifiers http://www.espas-fp7.eu/dataset/eiscat/myionosonde (myionosonde owned by eiscat) These urls can then resolve to XML-based descriptions (or RDF-XML, or both using HTTP content negotiation) depending on the agreed system architecture. -- Name -- local ID -- Definition -- The local part of the identifier (assigned by the owner) -- Name -- namespace -- Definition -- the namespace part of the identifier, agreed within ESPAS, e.g. 'stfc'. -- Name -- version -- Definition -- The version number of the object being identified -- Name -- creation date -- Definition -- Date when the object/record was first created -- Name -- last modification date -- Definition -- Date when the object/record was last modified (the most recent modification)