>In a table where I have the fields table.reg and table.ID
>
>How can I go bottom within a condition ?
>
>or
>
>How do I get the maximum table.reg for ID = 526 ?

You can't GO BOTTOM with the condition. You even GO BOTTOM or not :-)
If you wan to know what is max value for an ID you have several choices:
1. If you have an index based on ID and Reg (i.e. STR(Id)+STR(Reg) ), then you could set the order to that index DESC and seek for the ID (be sure that SET EXACT is OFF)
2. You could use SELECT:

SELECT MAX(Reg) FROM MyTable WHERE Id =526 INTO ....