$staticprop

From Valve Developer Community

The $staticprop QC command specifies that the model being compiled does not have any moving parts.

 Note: Despite the name, compiling with $staticprop does not limit the model to use with prop_static.

$staticprop does apply several useful optimisations to the model, so it should be used whenever possible:

• It collapses all bones in the model into a single, rigid bone; so do not use for models with skeletal animation or ragdoll behavior.
• VRAD will use the object's collision model when calculating Lightmaps.
• To do: Other?

QC syntax example

$modelname		"weapons/shell.mdl"
$staticprop
$cdmaterials		"models/weapons/"
$body		shell	"shell-ref.smd"
$sequence	idle	"shell-idle.smd"	// A default animation is still required

Note how the command does not accept any parameters.