ask one question about item range in e coverage

hi all,

    1.ask one question,i write the coverage code, the range option has four parameter,if i do not write the last three parameter,like:

............using ranges = {range([3]);range([5]);};....

the result is not what i want ,mostly ,e never collect the coverage data.

but if i write the code like this:

..........using ranges = {range([3],"3",UNDEF,1);range([5],"5",UNDEF,1)};........ the coverage data could work collectly,

i don't know why ,could you guys help me out of the doubt?????thanks in advance.

plus:i write the transition use illgeal option,i write item A use ranges = {range([3];range[5],range[7])},while this transition work correctly,,,,,i am totally confused.....

2.another question:

in coverage with e,we often use transition ,,,,,when we use illgeal or ignore,pre_item is always used.for example:

...

...

... 

transition st using illegal =
not ((prev_st == START and st == FETCH1)
or (prev_st == FETCH1 and st == FETCH2)
or (prev_st == FETCH1 and st == EXEC)
or (prev_st == FETCH2 and st == EXEC)
or (prev_st == EXEC and st == START));

the prev_item means the pre_value at the sample point, or the value last sampled???????

i look up for the answer in e_ref,,,but the explanation is not quite clear,,,,plz help me out.....