Why is it that I only accepted the offer and did not receive appointment letter?

Only thing that has my salary and leave entitlement is in the verbal offer email.

I always thought I had to sign on a document which clearly shows my job title and salary etc. but I was not told to sign a document like this.

The offer letter I signed merely showed my start date. Anyone had similar experience? How was your offer letter like? I.e. the one you signed formally did it contain other info?