If that part is successful, other manufacturers will develop substitute parts to match, either because there's a market-wide demand for the product, and/or because the original manufacturer licensed the design to others to assure a second-source supply of the part. Typically, one manufacturer will develop a part and offer it for sale. The 'OE' appears as abbreviation in truth tables, but for what it stands for you'll have to read the ICs description. For many parameters there are tables with a column 'symbol', and next to it a column 'parameter', which describes it briefly. I checked with a few datasheets from different manufacturers, and I must say, it might have been worse. That way they avoid datasheets becoming twice as long because they contain all this information time and again. The datasheet often refers to the Logic Family Guide, which contains information concerning the whole series. I never realized this before, but you're right: the datasheets have many terms and abbreviations which are not clearly explained. Reason: different trigger levels, these are not standardized. I remember a Schmitt-Trigger inverter I once use for an oscillator, which generated a complete different frequency when using make Y instead of X. Sometimes there are small differences in the details. These families have their particular properties, which you'll find in a 'Logic Family Guide'. The technology used may be different though a 74LS32 is low-power Schottky, while a 74HC32 is high speed CMOS. A 74xx32 is always a quad 2-input OR gate. Logic ICs with the same number have the same functionality and pinout across manufacturers.

Ttl ic 7400 datasheet