Schema of simple basic types used in various places in the SWE Common Data Model. SWE Common is an OGC Standard. Copyright (c) 2010 Open Geospatial Consortium. To obtain additional rights of use, visit http://www.opengeospatial.org/legal/ . Base substitution groups for all SWE Common objects other than value objects Extension slot for future extensions to this standard. Base substitution groups for all SWE Common objects with identification metadata Unique identifier of the data component. It can be used to globally identify a particular component of the dataset, a process input/output or a universal constant Textual label for the data component . This is often used for displaying a human readable name for a dataset field or a process input/output Textual description (i.e. human readable) of the data component usually used to clarify its nature This type specifies a character string of length at least one, and restricted such that it must not contain any of the following characters: ":" (colon), " " (space), (newline), (carriage return), (tab). This allows values corresponding to familiar abbreviations, such as "kg", "m/s", etc. It is also required that the symbol be an identifier for a unit of measure as specified in the "Unified Code of Units of Measure" (UCUM) (http://aurora.regenstrief.org/UCUM). This provides a set of symbols and a grammar for constructing identifiers for units of measure that are unique, and may be easily entered with a keyboard supporting the limited character set known as 7-bit ASCII. ISO 2955 formerly provided a specification with this scope, but was withdrawn in 2001. UCUM largely follows ISO 2955 with modifications to remove ambiguities and other problems. "now" indicates that the specified value shall be replaced with the current temporal position whenever the value is accessed.