The abbreviation for "Original Equipment Manufacture".
OPERATING TEMPERATURE RANGE
Temperature ranged over which the crystal characteristics are guaranteed.
OSCILLATION MODE
A quartz crystal is designed to vibrate on its fundamental frequency or one of its overtones. This becomes important between the 24MHz to 40MHz ranges. Crystals in that frequency range may be made as either a high fundamental or a low 3rd overtone. Fundamental mode crystals at these frequencies become more expensive, because the quartz blank is extremely thin, difficult to handle, and subject to a higher rate of breakage in processing. If you are able to use the 3rd overtone crystal instead of the fundamental, your cost savings may be significant. As the frequency range is extended, the oscillation mode of the crystal changes to other overtones. Crystals in the range of 60-110MHz are generally 5th overtones, while crystals in the range of 110-175MHz generally are 7th overtones.
OVERTONE
An odd numbered multiple of the fundamental frequency.
