Drafter Cody J. Guidry gives us a tip on how to create a user-defined parameter (and when to use one) in AutoCAD Civil 3D.

"This is a tip for creating points to use as labels in Civil 3D 2011. If you use Civil 3D, you should know how to make various point styles to fit your needs.

"Personally, I use points for labeling certain features in a drawing, e.g., points of intersection, survey benchmarks, etc. Sometimes I have to display three types of coordinates in the same label. Now two of them (northing, easting, latitude, and longitude) aren't difficult because it is based on the coordinate system that your drawing is set up for, e.g., NAD 83, Louisiana South Zone (U.S. foot). But say, for example, that you would like to display northing and easting in NAD 27, Louisiana South Zone (U.S. foot). You would have to do this a different way. This is where user-defined parameters (UDPs) come in handy.

"Go to the Settings tab in your toolspace and click on Point. The first thing you'll see in the tree is User-Defined Property Classifications; open that up, right-click, and choose Create New. Call it NAD 27, for this example. Now right-click on NAD 27 and choose Create New. You should have a box labeled New User Defined Property. Give it a name — call it Northing. Make sure the property field type says String. Click OK. Do the same thing for the easting coordinate.

"In your text editor on your point style, you can add two more fields: Nad 27 Northing and Easting. Now when you do a coordinate conversion with a program such as Corpscon, you can add two more fields for Northing and Easting for NAD 27 in your text file. To import the right information, you will have to create a point file format for importing this new file. I personally took the PNEZD format and saved it as PNEN27E27ZD, and added two more columns in my format file using the fields I just created. The only bad thing about all of this is that those two fields will not update automatically; if the point were to be moved, you would have to enter it manually in the point's property box.

"This will save time in the long run, and you can do this for other things as well. You can create a point file format for importing latitude and longitude instead of x and y. Try out UDPs for other features in Civil 3D. This is a great tool that is not mentioned often enough."
 
Notes from Cadalyst Tip Patrol: Civil 3D is a very powerful design tool from Autodesk. It is easy enough to set up custom text objects, such as that shown here, to annotate your drawings in a very automatic way. Define the fields and styles the way you want the text to be displayed, then apply it.