Yes the Z line (introduced 1986*) was upgraded to Z Custom in 93/94 according to that document. The smallest cymbal in the Z line was 13" Dyna Beat hats. No 12". No splash.
The first appearance of a Z or Z Custom splash is 1995. That is the 12" one. So if that's really a 12" cymbal then it should have a laser serial number. Unless for some reason Z Custom cymbals didn't get a laser stamp? I don't know much about Z line. It is also possible that there was a splash before the Z Custom upgrade, and it was missed out in the models document. If I get good evidence that there is an omission like that I'll put things right when I get my models lists and history added to my site.
* typo fixed where I had 1996 not 1986. Fumble fingers on the keyboard.
Hmm, something is amiss, I bought my 13" Z hats in 1986 or 87.
Multi-Hexagon pattern on top with big Z ink only.
Multi-star pattern on bottom, like as seen in the above photo. No ink on bottom.
Can't recall if they called them "Dyno-Beats" at that point yet, but I think they were.