This feature appeared for the first time with FileMaker 7 and it allows you to limit the number of characters that can be typed into a field. In a way, you had this option before with previous versions of FileMaker because you could use the Length function as part of a calculated validation option. However, this is much easier because all you do is check the box ( that you want to do it ) and then enter in the number of characters you want to be the upper limit.
Now some of you might be thinking,
“Hugh, why would the be that particular about the field length?”.
Hey! It’s (most likely) a layout appearance design limitation by the database author. Perhaps, they don’t want their users to get too verbose in their data entry. Although this may be a legitmate reason, there are more technical reasons as well.
As you know, FileMaker can communicate with other applications. They can send data to or retreive data from a number of database sources. What if those external sources had field limitations on the amount of text you can put into them? In fact, they do have limitations that you have to be aware of to communicate with them reliably.
The biggest thing I'm running to these days is with QuickBooks communication. I'm about to have my second database project fully communicate with QuickBooks. Some fields (such as company name) have size limitations. If I'm going to pass data reliably to them, I have to truncate the text at a cetain point. To make matters worse, some of these fields QuickBooks (not FileMaker) use a primary key fields! So they have to be unique! So I have to do two things, make the text smaller to fit in the limit and make sure it is attached to the correct primary key when passed to QuickBooks.
Other database engines and applications also can have rather limiting text character lengths on some of the key fields.