World: r3wp

I need to go now but your in good hands.

mhinson: OK, let's proceed further

so you are saying, that random-part may be a-word a-number or absent. 
This is it:

random-part: [a-word | a-number | none]

is this understood?

Thanks for your help Peter.  I am taking notes & understanding it 
I think.

Yes, that sounds a good description of the random part.

fine, we need to describe further, what is a-word:

a-word: [some alpha]

, is this adequate?

alpha: charset [#"a" - #"z" #"A" - #"Z"]

yes

fine, now for the a-number part. how big a number can it be?

1 to 2000 will cover it

a-number: [one-to-two 3 digit | non-zero-digit 0 2 digit]

hum..
a-number: [1 4 digit]
is that not enough ?

that allows for 0

as well as for 9999

that would be fine

ok then, you pick what is appropriate

yep but it's an average limit that mhinson gave

no need to be strict here, i think

repeated-part will not be the last thing on the line
: fine, what will be the last thing on the line?

(except for the newline character, of course)

will the newline character be actually there?

the final wanted bit of data will be the last thing, then the end 
of the line because the data has been read from the file with read/lines

how do you call the last part of the data, isn't it the same part 
that may repeat more than once?

(divided by comma, of course)

one more thing we need to make agreement on: do we want to rely on 
the default whitespace handling or be more specific and say exactly 
where whitespace may be?

well, it looks, that I will have to run soon

mhinson... If I can encourage you... once you will "get" it... it 
will all become <really> simple.  you mind is just adapting to maping 
rules and seeing the inherent stack of what they imply.  

Don't give up, it will all become clear.  I think we all feel the 
same anxiety at first.  Most don't follow through, its a good thing 
that you persevere.  :-)

the white space is not present in the intresting part of the data 
so would that suggest the default handleing would be ok?

you mean not using /all?

probably yes

yes

the rule

line: [random-part repeated-part any ["," repeated-part]]


just means, that at the start there is a special random-part, and 
then we have more repeated-part's separated by comma

notice, that the comma isn't at the end!

I dont understand why we need the repeated-part in twice?

we didn't specify what exactly is in the repeated-part, so we can 
continue:

repeated-part: [one-to-thirteen "/" a-range]

repeated-part twice: good question. we stated it so, to describe 
the situation, when the quantity of repeated-part's is one less than 
the quantity of commas

because of the comma (",")

sorry, "one more"

there is no comma before the first repeated-part, basically.

ok, bye, it's yours

Probably that would be enough:
line: [random-part any [repeated-part opt #","]]
But it can failed, dependening what is in repeated-part

well, that does not exactly describe what mhinson said

steeve, that means it will not require a comma, which means the repeated 
part can match some wrong pattern

agree, but if repeated part begins and ends with digits, it will 
not failed

hehe its hard not to help new users here.

but it WONT fail when they are missing, in which case your parse 
rules can wreak havoc.

the question there is, can the comma be missing ?

real test data
     3/1-2,3/4,3/7,3/26-30,3/34-38,3/48

3    4/1-2,4/4-13,4/15-17,4/19-21,4/23-25,4/27-28,4/30-33,4/35,4/40,4/48
4/36-39,4/41-47
35   4/29
40   4/18,4/22,4/26,4/34
999  4/3,4/14
disable     4/3,4/5,4/9,4/14,4/19,4/26,4/28,4/34,4/47

but i agree that Ladislav''s rule is more secure