class id filter

In the Selection filters/Combos filter, you can add class id filters in addition to registering superclassid filters. The bottom left list box displays a list of all helper and geometry class ids. To add a filter, select an entry from the list and hit the add button below the list box. The filter will appear in the lower right list box. This list displays all of the current class id filters. Once OK is pressed, the select filter drop down contains those class ids that were added.

You can also register custom scripted functions as filters through a callback in MAXScript:

Methods

registerSelectFilterCallback <filterFunction> <name>

Registers a custom selection filter. The 2 parameters are the filter function to be registered and the name of the filter to appear in the selection filter drop down list.

The filter function itself expects one parameter which is the node to be checked.

fn filterRenderableCallback node = --the node to be filtered is passed as argument
(
node.renderable --return true if the node is renderable
)
--Register the function as Select filter Callback function --The filter will appear under the name "Renderable":
registerSelectFilterCallback filterRenderableCallback "Renderable"
--To see how it works, execute the code below to generate 10 boxes --with random .renderable state
for i = 1 to 10 do
b = box pos:[i*30,0,0] renderable:((random 0.0 1.0) <0.5 )
--Now select the filter "Renderable" from the drop-down list and try --to select all 10 boxes - only those that are renderable will --be selected! 

Prototype:

unregisterSelectFilterCallback <filterFunction>

Removes the specified callback function from the list of selection filters.

unregisterSelectFilterCallback filterRenderableCallback