A satellite measurement a RINEX RTK arc builder left out of one epoch because no configured phase observable had a carrier frequency.

A GLONASS slot with no GLONASS SLOT / FRQ # channel, or with a channel outside the -7..6 FDMA allocation (real IGS headers give R28 channel 7), has no carrier. The builder forms each satellite's measurement from the first configured signal pair whose values are present and whose carriers resolve, so only a satellite no configured pair resolves for is left out and reported here; the rest of the epoch and the arc are built as usual. A left-out satellite has one entry for each phase observable, among the pairs whose values it held, with no carrier frequency, in pair order. receiver is :base or :rover, the file holding the measurement; epoch_index is the epoch's zero-based index in that receiver's file; observable_code is the full RINEX phase observable code, such as "L1C".