Arguments

method  (string, optional) specified the selection method (see Remarks); if not specified, a user-interactive selection is done
point1  (2d/3d point, optional) specifies the pick point or the first corner of crossing / windowing selection
point2  (2d/3d point, optional) specifies the second corner of crossing / windowing selection
pointList  (list of 2d/3d points, optional) specifies the list of polygon points for all polygon selection modes
filterList  (list, optional) filter to be applied to the created selectionset (post-processing the initially found selectionset)

Return

returns a selectionset (pickset), or NIL is selection failed

Example

(setq ss (ssget '((0 . "POINT"))))
interactive selection by user, then filters and returns only POINT entities in selectionset

(setq ss (ssget "I" (list (cons 0 "CIRCLE"))))
uses the already picked/selected entities (pickfirst set), then filters and returns only CIRCLE entities in selectionset

(setq ss (ssget "C" p1 p2 '((8 . "Basement"))))
creates a selectionset in "crossing" mode using the 2 points p1 and p2, then filters and returns only entities from layer "Basement"

(setq ss (ssget "X" (list (cons 0 "INSERT") (cons 62 "ByLayer")))))

creates a selectionset from entire database, filters and collects only BlockReferences with color "ByLayer"

Remarks

method :

A  AllVisible entities mode
B  Box mode

O  Outside mode
OP  OutsidePolygon mode
F  Fence mode
I  PickFirst mode
L  Last entity
P  Previously active selectionset
C  Crossing mode
CP  CrossingPolygon mode
W  Window mode
WP  WindowPolygon mode
X  Database mode

:E  Everything within aperture box around cursor position
:N  Nested entity selection
:S  Single selection only
:D  Duplicates allowed (not supported)
:U  Enables subentity selection
:V  Forced subentity selection

if method is NIL, then a point selection is processed at specified point1

filterList : a list of dotted-pairs ("filter item") of format (dxfCode . value), similar to the (entget) list format;
each dotted pair entry contains a required condition for the found entities; all conditions are applied in AND logic

'((0 . "LINE") (62 . 5))  selects only LINE entities, with color 5

for string values, wildcards are allowed;

"filter items" can be combined by logical and relational operators; both logical and relational filter items are specified by a -4 dxf Code

logical filter expressions :

"<AND" item ... item "AND>"  all filter items are combined via logical "AND" (all conditions must match)

"<OR"  item ... item "OR>"  all filter items are combined via logical "OR" operation (1 matching condition is sufficient)

"<XOR" itemA itemB "XOR>"  2 filter items are combined via logical "XOR" operation (1 and only 1 condition must match)

"<NOT" item "NOT>"  the filter item is used in inverted logic (condition does not match)

example : (ssget "X" '((-4 . "<OR") (0 . "CIRCLE") (0 . "LINE") (-4 . "OR>")))  selects all circle and line entities

relational filter expressions :

"*"  wildcard for "all"

"="  equal

"!="  not equal

"/="  not equal

"<>"  not equal

"<"  less than

"<="  less than or equal

">"  greater than

">="  greater than or equal

example : (ssget "X" '((0 . "ARC") (-4 . "<") (40 . 5.0)))  selects all arc entities with a radius less then 5.0