Anyone noticed why CFAI text spells Recognised and Amortised with the “S” and not with the “Z”?

CFA Level II
#1

Pension section snippet from CFAI:

Recognised immediately in P&L or, more commonly, recognised in OCI and subsequently amortised to P&L using the corridor or faster recognition method.b

  • Difference between expected and actual return on assets = Actual return – (Plan assets × Expected return).
  • Actuarial gains and losses = Changes in a company’s pension obligation arising from changes in actuarial assumptions.
#2

They’re trying to sound more gangsta.

#3

So? British English is standard with academic texts.