A \fIpick measure\fP resource must be created to actually perform
a pick operation.  A pick device type is specified at the time
a pick measure resource is created in order to provide the parameters
for the picking operation.  The pick measure resource accepts input
in the form of input records which are defined for each type of pick
device.  When a pick measure resource is passed a valid input record,
its attributes will be updated.
Pick measures
are lightweight resources, although the operations on a pick measure
resource are potentially lengthy since a great number of structure
elements may have to be processed in order to produce the pick results.
.LP
The pick measure resource components, in order,
are listed in the following table.
The abbreviation "from wks" indicates that the default
value is inherited from the pick device descriptor stored
in the PHIGS workstation resource when the pick measure is created.
.LP
.ID
.ta 0.1i 1.6i 2.8i
	\fBAttribute Name	Data Type	Default Value\fP
.ta
.ta 0.2i 1.5i 3.0i
	pick_status	{\fIOk, NoPick\fP}	from wks
	picked_prim	PICK_PATH	from wks
.ta
.DE
.LP
The attributes of the pick measure resource are defined as follows:

.Bl "pick_status"
This attribute contains the result of the last update operation that
was performed.  It is set to \fIOk\fP if a primitive was successfully
picked, and \fINoPick\fP if the pick operation was unsuccessful.

.Bl "picked_prim"
This attribute contains the path of the structure element that was
picked as a result of the last update operation.

.LP
The pick measure is an X11 resource and carries all of the 
responsibilities and
access rights of X11 resources.  The requests in this section
manage the creation and
freeing of pick measures.
