From BlenderWiki

Surface Selection

Surface selection in Edit mode is very similar to NURBS curve selection. The basic tools are the sames as with meshes, so you can select a simple control point with a LMB -click, add to current selection with ⇧ ShiftLMB -clicks, Border-select, and so on.

L (or CtrlL) will add to the selection the mouse cursor’s nearest control point, and all the linked ones, i.e. all points belonging to the same surface.

Select Menu

The Select menu (3D view headers) is even simpler than for curves…

Random...

Inverse

Select/Deselect All

Border Select

All these options have the same meaning and behavior as in Object mode (and the specificities of Border Select in Edit mode have already been discussed here).

Every Nth

This is the same option as for curve selection. However, the behavior of the N (“selection step”) parameter in the 2D of a NURBS surface “cage” seems quite difficult to understand…

Control Point Row

This option works a bit like edge loop selection for meshes, inasmuch it selects a whole row of control points, based on the active (the last selected) one. The first time you hit ⇧ ShiftR, the V-row passing through (containing) the active point will be added to the current selection. If you use again this shortcut, you will toggle between the U- and V-row of this point, removing everything else from the selection.

More and Less

These two options are complementary and very similar to those for meshes. Their purpose, based on current selected control points, is to reduce or enlarge this selection.

The algorithm is the same as with meshes:

• More: for each selected control point, select all its linked points (i.e. two, three or four).
• Less: for each selected control point, if all points linked to this point are selected, keep it selected. For all other selected control points, de-select them.

This implies two points:

• First, when all control points of a surface are selected, nothing will happen (as for Less, all linked points are always selected, and of course, More can’t add any). Conversely, the same goes when no control point is selected.
• Second, these tools will never “go outside” of a surface (they will never “jump” to another surface in the same object).