If there is no valid data for a cell of an EDM, it is better to leave the cell blank than to fill it with the word NULL.
The EDM indexer sees the value NULL in a cell as a token that needs to be indexed. This means the FileReader will be looking for the value of NULL in the message to match, rather than leaving it blank. Too many values that are the same value will cause indexing issues. Instead, leave the value blank.
For example, If you have an EDM with the following columns:
ID, Last Name, SSN, Credit Card, Account Number
If there is no Credit Card number in the account, that value should be left blank
The right way to enter this data is:
ID, Last Name, SSN, Credit Card, Account Number
1234, Smith, 123-45-6789,,987654