Well, to jump off Kerosene's "employers don't care" answer (I can't vouch for it's accuracy), neither does the FAA. There's nothing in FAR 61.51 that requires logging either HP or complex time and except for the commercial certificate, nothing that it needs to be counted for. From the FAA standpoint, it's an "acting PIC" issue not a logging one. If you are carrying totals for some non-FAA purpose, such as insurance requirements and the employer who may care, my bet is that someone who wants to know how much complex or HP time you have is asking under the current definition.
But to answer your specific question, there was an extensive rewrite of Part 61 in 1997. Before that, 61.31 didn't talk about "complex" airplanes at all. The definition of "high performance" included both. An HP airplane was one with an engine over 200 HP =or= one with flaps, controllable prop and retractable gear.
The change simply divided them into two categories. So, for example, a CE-172RG was a high performance airplane under the old rule but is not HP now.
You'll notice that the reference to August 4, 1997 also "grandfathers" certain people. If you logged PIC time in an airplane that is =now= defined as high performance (or complex) you don't need an endorsement under the new definitions.
So, as examples, if before August 4, 1997, the only non-simple airplane you logged PIC in was a CE-182, you don't need a HP endorsement, but need a complex one. On the other hand, if the only non-simple airplane you logged PIC in was a CE-172RG, you don't need a complex endorsement, but need a HP one.
Here's a hint to keeping it straight: Don't even think about the old rule definitions. They don't mean =anything= under the new ones. And neither does a pre-1997 endorsement - it's a historical memento with virtually no current legal significance whatsoever.
