The <Instrument_Identification> fields provide for the specification of keywords that are representative of the instrument being described. These keywords are important for the search and retrieval of information from the GCMD. The field, <Instrument_Identification>, consists of a 4-level hierarchical classification of instrument keywords. In addition, the field includes the short name and long name of the instrument.

• <Instrument_Category> is the top level classification of instruments, holding the following options:
  • Earth Remote Sensing Instruments
  • In Situ/Laboratory instruments
  • Solar/Space Instruments
• <Instrument_Class> is the second level classification under <Instrument_Category>. There are several controlled <Instrument_Class> keywords for each <Instrument_Category>.
• <Instrument_Type> is the third level classification under <Instrument_Category> <Instrument_Class>. There are several controlled <Instrument_Type> keywords for each <Instrument_Class>.
• <Instrument_Subtype> is the fourth level classification under <Instrument_Category> Instrument_Class > <Instrument_Type>. There are several controlled <Instrument_Subtype> keywords for each <Instrument_Type>.
• <Short_Name> is the abbreviated name of the instrument used to acquire the data. The <Short_Name> keyword must be selected from the set of defined instrument keywords. See http://gcmd.nasa.gov/add/difguide/sensor_name.html for more details on the instrument <Short_Name>. For example, <Short_Name>ASTER</Short_Name>
• <Long_Name> is the full name of the instrument used to acquire the data. See http://gcmd.nasa.gov/add/difguide/sensor_name.html for more details on the instrument <Long_Name>. For example, <Long_Name>Advanced Spaceborne Thermal Emission and Reflection Radiometer</Long_Name>

<Instrument_Identification>
<Instrument_Category>Instrument Category Keyword</<Instrument_Category>
<Instrument_Class><Instrument Class Keyword/<Instrument_Class>
<Instrument_Type>Instrument Type Keyword</<Instrument_Type>
<Instrument_Subtype>Instrument Subtype Keyword</<Instrument_Subtype>
<Short_Name>Short Name Keyword</<Short_Name>
<Long_Name>Long Name Keyword</<Long_Name>
</Instrument_Identification>

• With the exception of the <Short_Name>, <Instrument_Identification> fields may contain 1 to 160 characters. Characters include the entire printable UTF-8 character set.
• The <Short_Name> contains 1-31 characters. Characters include the entire printable UTF-8 character set. See: http://gcmd.nasa.gov/add/difguide/sensor_name.html.

• The <Instrument_Identification> field is required and may not be repeated.
• The following fields within <Instrument_Identification> are required and may not be repeated:
  • <Instrument_Category>
  • <Instrument_Class>
  • <Short_Name>
• The following fields within <Instrument_Identification> are optional and may not repeated:
  • <Instrument_Type>
  • <Instrument_Subtype>
  • <Long_Name>
• <Instrument_Identification> keywords must be selected from the set of defined keywords.

<Instrument_Identification>
<Instrument_Category>Earth Remote Sensing Instruments</Instrument_Category>
<Instrument_Class>Passive Remote Sensing</Instrument_Class>
<Instrument_Type>Spectrometers/Radiometers</Instrument_Type>
<Instrument_Subtype>Imaging Spectrometers/Radiometers</Instrument_Subtype>
<Short_Name>ASTER</Short_Name>
<Long Name>Advanced Spaceborne Thermal Emission and Reflection Radiometer</Long_Name>
</Instrument_Identification>