Answers to these and many others (like what's the difference between Verolog-A and Verilog-AMS) question can be found in the Language Reference Manual. Please visit the site: http://www.designers-guide.org/VerilogAMS/

Designer's guide community is extremely useful with verilog A.

Meanwhile,  will try to address your queries here.

1) Are u talking about contribution operator? I am not acquainted with distribution operator. Contribution operator is basically to assign (signal) values to the ports in very basic view.

2) transition filter is used to convert a discrete signal to a continuous signal but it has a linear transition between the two discrete states.

you should try checking slew operator and transition operator.

Dear all

While converting Discrete signal to continuous signal using transition filter, is it possible to get original signal? i mean accuracy of the signal.

Is it possible to convert from Continuous signal to discrete signal using transition filter?

There is a function absdelta() which converts an analog signal into a discrete one.