All professionals tend to screen their knowledge, or their lack of it, by using jargon.
Often these are abbreviations or acronyms. Computing is no different from any other profession. The letters IE4 or 5 in this paragraph, and in the lists below, if you allow your mouse pointer to dwell on the acronym the meaning will be displayed. But only in IE of course. Then when the surfer presses TAB the link will be positioned and highlighted.