As always in AutoCAD there are numerous ways to do the same thing, mainly due to the way the program has matured over the years. Items that existed way back in R12 are still there in R19.1 (2014), even if they have been replaced with a “better” implementation. These legacy options can sometimes be useful and also if you are encountering a problem its likely that something has been drawn using an older method that in not compatible with newer options.

Take for instance text suffices for dimensions. The usual way to append text is to either set it as default in the Dimension Style Editor or append it for an individual dimension using the properties box (see above).
However you can also append text using <> then whatever text in the Text Override box. This is useful as you can have this as well as a Prefix and a Suffix. The <> represents the dimension. For instance if I have a prefix of SO and a suffix of mm, I can use the following in the Text Override,
Overall <> opening
to achieve,
Overall SO 1045mm opening
This can be useful for one off dimensions where the text needs to be padded out to make the dimension clearer and the dimension style is carrying suffices that are required to be kept.

The override box can also be used to place text below the dimension line whilst the dimension remains above. This is done using the <> X modifier! For example;
<> XTEXT

Note that if you want the text to be centred no space is required between “X” and the text required otherwise a space precedes the text below the line.
The major drawback with using text override as the main method for applying suffices is that Match Properties will not carry the text override from one dimension to another, it has to be retyped, whereas a dimension with Suffix used will carry over.