The Poly Select modifier lets you pass a sub-object selection up the stack to subsequent modifiers. It provides a superset of the selection functions available in Editable Poly. You can select vertices, edges, borders, polygons, and elements. You can change the selection from sub-object level to object level.
When you apply the Poly Select modifier and then go to any sub-object level, the select-and-transform buttons in the toolbar are unavailable, and the Select Object button is automatically activated.
When you apply a Poly Select modifier, there are no animation controllers assigned to the sub-object selection. This means that the selection has no way to "carry" the transform information needed for animation.
To animate a sub-object selection using Poly Select, apply either an XForm or Linked XForm modifier to the selection. These modifiers provide the necessary controllers for animating the effects of transforms. In a sense, they give "whole-object status" to the sub-object selection.
Animates transforms directly on a sub-object selection. Creates a gizmo and center for the sub-object selection. You can animate both, with the center acting as a pivot point for the selection.
Lets you choose another object to control the animation. The sub-object selection is linked to the "control object." When you transform the control object, the sub-object selection follows accordingly.
To use the Poly Select modifier:

Selects vertices.
Selects edges.
Selects borders.
Selects polygons.
Selects elements.
For more information on the stack display, see Modifier Stack.

Provides buttons for accessing different sub-object levels, working with named selections and handles, display settings, and information about selected entities.
The icons at the top of the Selection rollout let you specify the method of face selection.
Clicking a button here is the same as choosing a sub-object type in the modifier stack. Click the button again to turn it off and return to the Object selection level.
and
keys:
held down converts the current selection to the new level, selecting all sub-objects in the new level that touch the previous selection. For example, if you select a vertex, and then
+click the Polygon button, all polygons that use that vertex are selected.
and
as you change the level. For example, if you convert a vertex selection to a polygon selection with
+
+click, the resultant selection includes only those polygons all of whose vertices were originally selected. When the Border sub-object level is active, you can't select edges that aren't on borders. Clicking a single edge on a border selects that whole border.
Borders can be capped (either in editable poly or by applying the cap holes modifier). They can also be connected to another object (compound object connect).
Backface Cull setting doesn't affect sub-object selection. Thus, if Ignore Backfacing is turned off, you can select sub-objects even if you can't see them. For this function, a border is considered to be an edge selection.

With Shrink and Grow, you can add or remove neighboring elements from the edges of your current selection. This works at any sub-object level.

Ring selection adds to the selection all the edges that are parallel to the ones selected originally.
Loop applies only to edge and border selections, and propagates only through four-way junctions.

Loop selection extends your current edge selection by adding all the edges aligned to the ones selected originally.
Applies selections from one sub-object level to another.
Selects faces based on their material ID.
while clicking to add to the current selection, or press
to remove from the current selection. These functions are primarily for copying named selection setsof sub-objects between similar objects, and between comparable modifiers and editable objects. For example, you can apply a Poly Select modifier to a sphere, create a named selection set of edges, and then copy the selection to a different sphere that's been converted to an editable mesh object. You can even copy the selection set to a different type of object, because the selection is identified by the entities' ID numbers.
The standard procedure is to create a selection set, name it, and then use Copy to duplicate it into the copy buffer. Next, select a different object and/or modifier, go to the same sub-object level as you were in when you copied the set, and click Paste.
Soft Selection controls affect the action of sub-object Move, Rotate, and Scale functions. When these are on, 3ds Max applies a spline curve deformation to unselected vertices surrounding the transformed selected sub-object. This provides a magnet-like effect with a sphere of influence around the transformation.
For more information, see Soft Selection Rollout.