Hello Arthur, 

You can't assign a sequence number as you normally do for Product number or PIH/SIH document numbers.

But you can programmatically get the next number from a sequence and use it to fill your field value.

You can use the function NUMERO just like this example.

Call NUMERO (NOME_CONTADOR, ESTAB, [0/0/0], "", CONTADOR, STAT) From SUBANM

http://online-help.sageerpx3.com/erp/11/staticpost/get-a-sequence-number-value/

Perfect, I get it! Thank you so much for your kind answer.

And in another way, changing the scope... If I change the idea of sequential numbers to status based, for example, I have a custom table with two columns, number and status, and every new record, such as a new Purchase Invoice-record, the system will automatically get the value from this table which has the status "Current" and fill in a custom field located on the Purchase Invoice screen. Only in new records.
In other words, it would be possible to bring a value from other table based on a criterion triggered for new records?

Thank you again,

Regards,