Station and network coding systems are necessary in order to facilitate data exchange: when dealing with data coming from different networks, it is necessary to ensure that any station is identified by a single code. In addition, station code enable proper archiving of station information and provide appropriate means of recognizing and acknowledging the organizations and institutions who are the network/station operators and data providers.
There are currently 2 station coding systems, the one practiced by the parametric data centres, e.g. ISC, NEIC and EMSC through the International Registry (IR) and the other practiced by the broad-band station/network operators of FDSN (Federation of Digital Seismic Network).
The spread use of seismic arrays of small aperture having several stations within 1 km from one another, collocation of different seismic instruments at the same site, different agencies using the same site to install their seismic stations, different agencies providing measurements of arrival time and amplitudes from the same seismograms and more, result in a situation were the 3-5 characters code name (as practiced in the International Registry) can no longer accommodate the need to uniquely identify the station and source of information.
Apparently, these problems concern more the parametric data centre. However, many will consider the 3-5 character code name insufficient for uniquely characterizing the stations in the FDSN system although the relatively lower number of operating BB stations (as compared to SP) and the fact that waveform data exchange provide much information in the data header, helps overcoming many of the shortcomings of the current station code. However, the FDSN coding system introduces a 2 characters network code. This restriction does not allow institutions to use their own institute abbreviations, if they so prefer.
We should also take into account the fact that modern strong motion instruments may well serve the community like other seismic stations (within the limits of the dynamic range and frequency band). Accelerometers are currently not included in the IR or the FDSN systems and it is essential to include this type of instruments in the station coding systems.
Following these and other practical difficulties, the parametric data centres NEIC, EMSC and ISC took the initiative to propose a working group within the Commission On Seismological Observation and Interpretation (COSOI) to view the advantages and disadvantages of the current practices and suggest an alternative system if and when appropriate.
The establishment of the WG on Seismic Station Codes has been approved by IASPEI/COSOI at the IASPEI general Assembly in Santiago, Chile in 2005.
Seismic Station Codes - New Recommendations (Draft Version)