>Hello There...
>
> First of all, wish a Merry Christmas and a Happy New Year to every member.
>
> I need to implement security mechanism over my tables. I've heard before that every table have a header, and that if someone alterate the header, the table won't work until the values in the header are corrected again. I think this is kind of a cool way to secure our data. The only problem is "How can I edit the values in the header of every table"?
>
> I hope someone knows the answer to this "simple question".
>
>Onelio Dishmey C.
>onedish@hotmail.com

It'd not secure your data. It's easy to create a header for data and read it or directly read using notepad.
If you want just to make a nonworking header simply :

lnHandle = fopen('myDBF.dbf',12)
fwrite(lnHandle,chr(0))
fclose(lnHandle)

It's not a simple question "How can I edit the values in the header of every table"? A simple but cumbersome way would be :

do home()+'tools\hexedit\hexedit' with 'myTable.dbf'

Of course what you want is how to do that programmatically but it doesn't make sense now if it's no good for protection. Protection somewhat depends on what level you want it and a simple one might be to use dbc_events to control opening of tables. Cryptor from www.xitech-europe.co.uk might be another better solution or going to client/server.

Happy new year
Cetin