Although fields have been around in AutoCAD since 2005, they only appeared in LT in this last version. (Hey, better late than never.)
Fields are special text objects that store the properties of objects or the drawing. You can use them to display the length of a line, the area of a polyline, or the name of a layout. When the property changes, the field will update after a regen.
For a quick example, let’s say you have a rectangle. If you wanted to display the area of that rectangle, you could list it, copy the area from the list data, go back to the drawing, create a piece of text, and paste the data into the text box. Now, that’s not very complicated (although it is a lot of steps), but what if the rectangle changes size? With plain text, you’d have to go through that all again. Instead, you can create a field that displays the area, and that will update automatically.
Under the Text tab of the Annotate Panel, select Insert Field. For the Field Category and Field Name, choose Objects (since you’re working with a rectangle), and use the Select Object icon to select the rectangle. Once it’s selected, highlight Area, and Architectural Units, and click OK. One more click to place the field, and you're done.
The grey background behind the text identifies this particular object as a field. Now, let’s say you need to make the rectangle bigger. You can stretch one side, regenerate the drawing, and there it is – the field is now displaying the new area.
This is only one of the many possible applications for fields – I’m sure you have some more in mind!
You can see a field in action at the end of this video (after the other new-to-LT features).