The figure below shows the GX6264 instrument. The instrument is available in two versions; a commercial version using plastic packaging for the relays and an industrial version (also named Hi-REL) using metal packaging providing higher reliability and current rating over the plastic packaged version. All functions on these two boards are identical.
GX6264 Switching Instrument
The lower half consists of scan groups A-D (Section 1) and the upper half consists of scan groups E-H (Section 2).