was developed by the Australian broadcaster, uses 48 kHz 16-bit two-channel WAV files, which is identical to that of Digital Audio Tape. The Digital Radio Mondiale consortium uses WAV files as an informal standard for transmitter simulation and receiver testing. Limitations The WAV format is limited to files that are less than 4 GiB, because of its use of a 32-bit unsigned integer to record the file size header. Although this is equivalent to about 6.8 hours of CD-quality audio (44.1 kHz, 16-bit stereo), it is sometimes necessary to exceed this limit, especially when greater sampling rates, bit resolutions or channel count are required. The W64 format was therefore created for use in Sound Forge. Its 64-bit header allows for much longer recording times. The RF64 format specified by the European Broadcasting Union has also been created to solve this problem. Non-audio data Since the sampling rate of a WAV file can vary from 1 Hz to 4.3 GHz, and the number of channels can be as high as 65535, .wav files have also been used for non-audio data. LTspice, for instance, can store multiple circuit trace waveforms in separate channels, at any appropriate sampling rate, with the full-scale range representing ±1 V or A rather than a sound pressure. Audio compact discs Audio compact discs (CDs) do not use the WAV file format, using instead Red Book audio. The commonality is that audio CDs are encoded as uncompressed pulse-code modulation (PCM), which is one of the formats supported by WAV. WAV is a file format for a computer to use that cannot be understood by most CD players directly. To record WAV files to an Audio CD the file headers must be stripped, the contents must be transcoded if not already stored as PCM, and the PCM data written directly to the disc as individual tracks with zero-padding added to match the CD's sector size. In order for PCM audio to be able to be burned to a CD, it should be in the 44.1 kHz, 16-bit stereo format. Comparison of coding schemes Audio in WAV files can be encoded in a variety of audio coding formats, such as GSM or MP3, to reduce the file size. This is a reference to compare the monophonic (not stereophonic) audio quality and compression bitrates of audio coding formats available for WAV files including PCM, ADPCM, Microsoft GSM 06.10, CELP, SBC, Truespeech