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Definition of identifiers

Data sources are uniquely identified using a sequence of codes named network, station, location and channel, where the channel is further subdivided into band, source and subsource codes. Each of these codes must be composed of the following ASCII character sets:

  • Uppercase [A-Z], ASCII 65 through 90

  • Numeric [0-9], ASCII 48 through 57

The station and location codes may further be composed of the following ASCII character:

  • Dash “-”, ASCII 45

The codes are further defined as follows:

Network code: Uniquely identifies the owner and network operator responsible for the data. Network codes are assigned by the FDSN. Must be between 1 and 8 characters. Further description of Network codes.

Station code: Uniquely identifies a station within a network. Station codes may be registered with the International Registry of Seismograph Stations. Must be between 1 and 8 characters. Otherwise, these may be whatever the operator wishes.

Location code: Uniquely identifies a group of channels within a station, for example from a specific sensor or sub-processor. Must not exceed 8 characters. The special value of “–” (two dashes) is forbidden as it conflicts with previous usage for designating empty locations. Further description of Location codes.

Channel: A sequence of codes that identify the band, source and subsource. Definition and values for each of these codes are in Channel codes.

Band: Indicates the sampling rate range and response band of the data source.

Source: Identifies an instrument or other data source.

Subsource: Identifies a sub-category within the source.

Source Identifiers

The FDSN Source Identifier (SID) is a combination of the network, station, location, band, source and subsource codes into a Uniform Resource Identifier (URI). The pattern of the Source Identifier is as follows:

For identifying a data source, i.e. a specific channel:

FDSN:<network>_<station>_<location>_<band>_<source>_<subsource>

where the network, station and source codes are required to be non-empty. The underscore (ASCII 95) delimiters must always be present.

Abbreviations of the fully qualified identifer may also be used to identify higher hierarchical levels such as a location (a collection of specific channels within a station), a station within a network, and a network as follows:

FDSN:<network>_<station>_<location>
FDSN:<network>_<station>
FDSN:<network>

Example identifiers:

FDSN:IU_COLA_00_B_H_Z

where network=IU, station=COLA, location=00 and channel=B_H_Z

FDSN:NL_HGN__L_H_Z

where network=NL, station=HGN, location is empty and channel=L_H_Z

The FDSN: portion is a namespace identifier reserved to identify this specification.

Mapping of SEED 2.4 codes

In the SEED 2.4 standard, data sources are identified by a combination of network, station, location and channel codes, abbreviated here as a NSLC. A NSLC can always be mapped to a Source Identifier. Conversely, so long as each code is within the length restrictions imposed by SEED 2.4, Source Identifiers can be also be mapped back to SEED 2.4 codes. The mapping is as follows:

From SEED NSLC to Source Identifier

Network codes

The 1 to 2 character network code is mapped without change.

For temporary networks, starting with X, Y, Z or 0-9, the 2 character network code may be mapped either unchanged, or may follow the Transitional mapping of previously allocated temporary network codes by appending the start year to create a 6 character code, when the 6-character code has been allocated by the FDSN.

Station codes

The 1 to 5 character station code is mapped without change.

Location codes

The 0 to 2 character location code is mapped without change.

Channel codes

The 3-character channel codes are split into the three single character band, instrument and orientation codes, which are mapped to the Source Identifier (Channel codes) band, source and subsource codes.

Examples

Permanent network NSLC: ‘IU’, ‘ANMO’, ‘00’, ‘BHZ’ maps to FDSN:IU_ANMO_00_B_H_Z

Permanent network NSLC: ‘IU’, ‘ANMO’, ‘’, ‘BHZ’ maps to FDSN:IU_ANMO__B_H_Z

Temporary network starting in 2002 NSLC: ‘XA’, ‘ABCD’, ‘00’, ‘BHZ’ maps to FDSN:XA_ABCD_00_B_H_Z or to FDSN:XA2002_ABCD_00_B_H_Z

From Source Identifier to SEED NSLC

Network codes

Codes from 1 and 2 characters are mapped without change. Network codes following the 6-character Transitional mapping of previously allocated temporary network codes are mapped using just the first 2 characters of the code, removing the 4 character year. Otherwise, there is no mapping for network codes greater than 2 characters.

Station codes

Codes from 1 to 5 characters are mapped without change. There is no mapping for stations codes greater than 5 characters.

Locations codes

Codes from 0 and 2 characters are mapped without change. There is no mapping for location codes greater than 2 characters.

Channels codes

Code combinations where the Source Identifier (Channel codes) band, source and subsource codes are all 1 character each, are concatenated in this order and mapped to the 3 character NSLC channel codes. Otherwise, there is no mapping when individual codes are greater than 2 characters.

Examples

Permanent network FDSN:IU_ANMO_00_B_H_Z maps to NSLC: ‘IU’, ‘ANMO’, ‘00’, ‘BHZ’

Permanent network FDSN:IU_ANMO__B_H_Z maps to NSLC: ‘IU’, ‘ANMO’, ‘’, ‘BHZ’

Temporary network starting in 2002 FDSN:XA_ABCD_00_B_H_Z maps to NSLC: ‘XA’, ‘ABCD’, ‘00’, ‘BHZ’

Temporary network starting in 2002 FDSN:XA2002_ABCD_00_B_H_Z maps to NSLC: ‘XA’, ‘ABCD’, ‘00’, ‘BHZ’