What do you think this is? [1]
mech_eng_jw.pdf
Or maybe
datasheet.pdf ?
And why do some PDFs page continuously and some jump between pages? You can't even see all of the stuff on the jumpers.
And why do some web sites, especially Asian and European ones, make you sequentially open a huge list of randomly named PDFs to see what they have?
And why do some people use one data sheet to cover their entire product line, with complicated made-up part numbers, most not available in stock anywhere? That's typically european.
[1] it's a data sheet for a relay