in the transport request only task no and request  no are
there and task no contains the activities and when the
request is released task no is released first then request
no is released.

for cash sale the schedule line is cs,there u dont find any 
availability check, nor requrments checked,nor ur porduct 
allocation is also not checked.correct me if iam wrong

Jayesh is very close to the answer.
In a cash sale, the customer receives the goods immediately 
and payment is done at the same time. The delivery document 
is created. The billing can be done later on. 
 If and only if the goods are available, the cash sale 
transaction takes place. Hence, no availability check is 
carried out in cash sale.

Pavan Is right, in sales order by configuring we can see 
directly what the closing stock in plant for the product 
based on this we can sell the goods in CS.