very urjent in table maintanace generator

Hi Experts,

I am new to table maintenance generator, i got below issue can u please guide on this.

I am having two customized tables ZARCAT, ZARCAT.

Is there any of the one of the events available before output or make the modification in the screen directly by coding F4 help. (in this case as and when table maintenance is generated code will be lost so we have to be careful) .

2) We need to put validation in "before saving data" event that if all the fields Ccode + Category + GL Account + Doc type are blank then raise an error message "All Fields Cannot be Initial"

This can happen only once since this is the primary key, but we need to make sure there are no blanks otherwise it will affect the report selection and layout both.

3) Validations to be built on ZARCAT table maintenance ,

a) Category code should not be initial

b) Check that no user is able to delete category code 00 and 99 (since these pertain to Opening bal and Closing Bal ) .

c) Field colseq should never be blank

d) Whenever SUBTOTFR is entered check that SUBTOTTO is also entered and

e) Validate SUBTOTFR is not greater that SUBTOTTO .

f) SHKZG should not be initial on any record

g) CATDESC should not be initial.

All these validations can be done using events.

Thanks in advance,

Mahamood.