The Maximum Operating Temperature is the maximum body temperature at which the thermistor is designed to operate for extended periods of time with acceptable stability of its electrical characteristics.
the amount of capacitance measured or computed across the crystal terminals on the PCB. Frequency Tolerance. Frequency tolerance refers to the allowable deviation from nominal, in parts per million (PPM), at a specific temperature, usually +25°C.
the maximum allowable deviation from the nominal crystal frequency at a specified temperature, usually 25℃. The recommended frequency tolerance of the crystal over the manufacturing process is ±50 ppm.
IP (or "Ingress Protection") ratings are defined in international standard EN 6529 (British BS EN 6529:1992, European IEC 659:1989). They are?used to define levels of sealing effectiveness of electrical enclosures against intrusion from foreign bodies?(tools, dirt etc) and moisture.