About the legality of read-write files of propietary soft.

I'd want to know your experience and know-how about the legality or not of:

I have the next question grid :

Fully Free software LPGL Software Nonfree software
Read ascii
Read ascii that has
some coding

write ascii
write scii that has
some coding

Read ascii
Read ascii that has
some coding

write binary
write binary that has
some coding

1. In the case of ascii coding we can assume that is easy to discover.
2. In the case of binary coding, we can assume that some inverse engineering is needed to know how is the structure of the file and the meaning of codes..
3. We can assume we are doing import - export utilities.
4. What can be happen if we are writing into an existing file created by the original soft.?

Thanks

What is it exactly that you want from us? What is "fully free software"? Is LGPL software not a "fully free software" too?

Maybe the whitespaces confuses.....
I want to you to fill this 'quiz'
( Can I read/write files created by other program, for example Excel.Autocad,etc)

(Yes is legal, No is not legal)

---------------------------- Fully Free software --------LPGL Software -------------- NON free software
Read ascii ..................................... Yes .......................... Yes .............................. NO
------------------------------ ------------------------------ --------------------------------- ----------------------
Read ascii that has ......................... Yes .......................... Yes .............................. NO
some coding
------------------------------ ------------------------------ --------------------------------- ----------------------
write ascii
------------------------------ ------------------------------ --------------------------------- ----------------------
write ascii that has
some coding
------------------------------ ------------------------------ --------------------------------- ----------------------
Read binari
------------------------------ ------------------------------ --------------------------------- ----------------------
Read binary that has
some coding
------------------------------ ------------------------------ --------------------------------- ----------------------
write binary
------------------------------ ------------------------------ --------------------------------- ----------------------
write binary that has
some coding
------------------------------ ------------------------------ --------------------------------- ----------------------

1. In the case of ascii coding we can assume that is easy to discover.
2. In the case of binary coding, we can assume that some inverse engineering is needed to know how is the structure of the file and the meaning of codes..
3. We can assume we are doing import - export utilities.
4. What can be happen if we are writing into an existing file created by the original soft.?


( In other words can I read-write autocad DWG files / PDF / MS word doc ...)

Thanks

What does licencing of the program has to do with file formats it uses? Reverse engineering is either allowed in your country or forbidden. Licence of the application is irrelevant. Just consider MS Word and Adobe Acrobat - both are "non-free" as you call it yet 1) there exist programs operating on the same file formats and 2) PDF specification is well known while doc specification has never been published.