The Platform or <Source_Name> is the name of the platform used to acquire the data, There are 11 categories of  platforms, with additional levels of hierarchical classifications (see the Writer's Guide for Ancillary Descriptions):

• Aircraft
• Balloons/Rockets
• Earth Observation Satellites
• In Situ Land-based Platforms
• In Situ Ocean-based Platforms
• Interplanetary Spacecraft
• Maps/Charts/Photographs
• Models
• Navigation Platforms
• Solar/Space Observation Platforms
• Space Stations/Manned Spacecraft

When using the GCMD metadata authoring tools, <Source_Name> classifications are automatically populated by selecting the <Short_Name>.
This field allows for the specification of keywords that are representative of the platform(s) or source used to collect the data.  These keywords are important for the search and retrieval of information from the GCMD.  The field <Source_Name> consists of the short name and the long name of the platform (source). There is a 1:1 correspondence between the short name and the long name.

• <Short_Name> is the abbreviated name of the platform (source) used to acquire the data.
• <Long_Name> is the full name of the platform (source) used to acquire the data.

<Source_Name>
   <Short_Name>Platform Short Name keyword</Short_Name>
   <Long_Name>Platform Long Name keyword</Long_Name>
</Source_Name>

• The <Source_Name> field is highly recommended and may be repeated as many times as necessary.
• <Short_Name> 1 to 80 characters from the UTF-8 character set, except “>”
• <Long_Name> 1 to 160 characters from the UTF-8 character set, except “>”
• <Short_Name> and <Long_Name> must be selected from the controlled set of Platform keywords. However, new platform identifiers may only be added if the platform does not already appear in the Platform Keyword List.
• The <Short_Name> is usually a mnemonic or abbreviated version of the <Long_Name>.  When submitting a new <Short_Name>, always check the Platform Keyword List to ensure mutual exclusivity among platform short names.  No two platforms may have the same <Short_Name>.

<Source_Name>
   <Short_Name>AQUA</Short_Name>
   <Long_Name>Earth Observing System, AQUA<Long_Name>
</Source_Name>

<Source_Name>
   <Short_Name>AUVS</Short_Name>
   <Long_Name>Autonomous Underwater Vehicles</Long_Name>
</Source_Name>