by Vadim Pavlov
http://doc.thesa.ru

PostScript Operators Quick Reference

This document contains summary information about all the standard operators in the PostScript language, organized into groups of related functions. Each operator description is presented in the following format:

operand1 operand2 ... operandn

operator

result1 ... resultm

explanation of the operator

At the head of an operator description, operand₁ through operand_n are the operands that the operator requires, with operand_n being the topmost element on the operand stack. The operator pops these objects from the operand stack and consumes them. After executing, the operator leaves the objects result₁ through result_m on the stack, with result_m being the topmost element.

Normally, the operand and result names suggest either their types or their uses. The table below shows common operand and result types used in this reference.

	Name	Description
	angle	Angle (in degrees)
	any	Value of any type
	boot	Boolean (true or false) value
	context	Integer representing an execution context
	dict	Dictionary object
	font	Font dictionary
	form	Form dictionary
	halftone	Halftone dictionary
	int	Integer number
	matrix	Array of six numbers describing a transformation matrix
	num	Number (integer or floating point)
	numarray	Array of numbers
	numstring	Encoded number string
	pattern	Pattern dictionary
	proc	Procedure (executable array or executable packed array)
	real	Floating point (real) number
	userpath	Array of path construction operators and their operands

Some operators are polymorphic: their operands may be any of several types. For example, the notation file | proc | string indicates an operand that is a file, procedure, or string.

The notation "|-" indicates the bottom of the stack. The notation "-" in the operand position indicates that the operator expects no operands, and a "-" in the result position indicates that the operator returns no results.

The documented effects on the operand stack and the possible errors are those produced directly by the operator itself. Many operators invoke arbitrary PostScript language procedures. Such procedures can have arbitrary effects that are not mentioned in the operator descriptions.

Operand Stack Manipulation Operators
any		pop	-	discard top element
any1 any2		exch	any2 any1	exchange top two elements
any		dup	any any	duplicate top element
any1 ... anyn n		copy	any1 ... anyn any1 ... anyn	duplicate top n elements
anyn ... any0 n		index	anyn ... any0 anyn	duplicate arbitrary element
an-1 ... a0 n j		roll	a(j-1) mod n ... a0 an-1 ... aj mod n	roll n elements up j times
|- any1 ... anyn		clear	|-	discard all elements
|- any1 ... anyn		count	|- any1 ... anyn n	count elements on stack
-		mark	mark	push mark on stack
mark obj1 ... objn		cleartomark	-	discard elements down through mark
mark obj1 ... objn		counttomark	mark obj1 ... objn n	count elements down to mark
Arithmetic and Math Operators
num1 num2		add	sum	num1 plus num2
num1 num2		div	quotient	num1 divided by num2
int1 int2		idiv	quotient	integer divide
int1 int2		mod	remainder	int1 mod int2
num1 num2		mul	product	num1 times num2
num1 num2		sub	difference	num1 minus num2
num1		abs	num2	absolute value of num1
num1		neg	num2	negative of num1
num1		ceiling	num2	ceiling of num1
num1		floor	num2	floor of num1
num1		round	num2	round num1 to nearest integer
num1		truncate	num2	remove fractional part of num1
num		sqrt	real	square root of num
num den		atan	angle	arctangent of num/den in degrees
angle		cos	real	cosine of angle (degrees)
angle		sin	real	sine of angle (degrees)
base exponent		exp	real	raise base to exponent power
num		ln	real	natural logarithm (base e)
num		log	real	logarithm (base 10)
-		rand	int	generate pseudo-random integer
int		srand	-	set random number seed
-		rrand	int	return random number seed
Array Operators
int		array	array	create array of length int
-		[	mark	start array construction
mark obj0 ... objn-1		]	array	end array construction
array		length	int	number of elements in array
array index		get	any	get array element indexed by index
array index any		put	-	put any into array at index
array index count		getinterval	subarray	subarray of array starting at index for count elements
array1 index array2		putinterval	-	replace subarray of array1 starting at index by array2
any0 ... anyn-1 array		astore	array	pop elements from stack into array
array		aload	a0 ... an-1 array	push all elements of array on stack
array1 array2		copy	subarray2	copy elements of array1 to initial subarray of array2
array proc		forall	-	execute proc for each element of array
Packed Array Operators
any0 ... anyn-1		packedarray	packedarray	create packed array consisting of the specified n elements
-		currentpacking	bool	return array packing mode
bool		setpacking	-	set array packing mode for {...} syntax (true = packedarray)
packedarray		length	int	number of elements in packedarray
packedarray index		get	any	get packedarray element indexed by index
packedarray index count		getinterval	subarray	subarray of packedarray starting at index for count elements
packedarray		aload	a0 ... an-1 packedarray	push all elements of packedarray on stack
packedarray1 array2		copy	subarray2	copy elements of packedarray2 to initial subarray of array2
packedarray proc		forall	-	execute proc for each element of packedarray
Dictionary Operators
int		dict	dict	create dictionary with capacity for int elements
-		<<	mark	start dictionary construction
mark key1 value1 ... keyn valuen		>>	dict	end dictionary construction
dict		length	int	number of key-value pairs in dict
dict		maxlength	int	current capacity of dict
dict		begin	-	push dict on dictionary stack
-		end	-	pop dictionary stack
key value		def	-	associate key and value in current dictionary
key		load	value	search dictionary stack for key and return associated value
key value		store	-	replace topmost definition of key
dict key		get	any	get value associated with key in dict
dict key value		put	-	associate key with value in dict
dict key		undef	-	remove key and its value from dict
dict key		known	bool	test whether key is in dict
key		where	dict true or false	find dictionary in which key is defined
dict1 dict2		copy	dict2	copy contents of dict1 to dict2
dict proc		forall	-	execute proc for each element of dict
-		currentdict	dict	push current dictionary on operand stack
-		errordict	dict	error handler dictionary
-		$error	dict	error control and status dictionary
-		systemdict	dict	system dictionary
-		userdict	dict	writable dictionary in local VM
-		globaldict	dict	writable dictionary in global VM
-		statusdict	dict	product-dependent dictionary
-		countdictstack	int	count elements on dictionary stack
array		dictstack	subarray	copy dictionary stack into array
-		cleardictstack	-	pop all non-permanent dictionaries off dictionary stack
String Operators
int		string	string	create string of length int
string		length	int	number of elements in string
string index		get	int	get string element indexed by index
string index int		put	-	put int into string at index
string index count		getinterval	substring	substring of string starting at index for count elements
string1 index string2		putinterval	-	replace substring of string1 starting at index by string2
string1 string2		copy	substring2	copy elements of string1 to initial substring of string2
string proc		forall	-	execute proc for each element of string
string seek		anchorsearch	post match true or string false	determine if seek is initial substring of string
string seek		search	post match pre true or string false	search for seek in string
string		token	post token true or false	read token from start of string
Relational, Boolean, and Bitwise Operators
any1 any2		eq	bool	test equal
any1 any2		ne	bool	test not equal
num1 | str1   num2 | str2		ge	bool	test greater or equal
num1 | str1   num2 | str2		gt	bool	test greater than
num1 | str1   num2 | str2		le	bool	test less or equal
num1 | str1   num2 | str2		lt	bool	test less than
bool1 | int1   bool2 | int2		and	bool3 | int3	logical | bitwise and
bool1 | int1		not	bool2 | int2	logical | bitwise not
bool1 | int1   bool2 | int2		or	bool3 | int3	logical | bitwise inclusive or
bool1 | int1   bool2 | int2		xor	bool3 | int3	logical | bitwise exclusive or
-		true	true	push boolean value true
-		false	false	push boolean value false
int1 shift		bitshift	int2	bitwise shift of int1 (positive is left)
Control Operators
any		exec	-	execute arbitrary object
bool proc		if	-	execute proc if bool is true
bool proc1 proc2		ifelse	-	execute proc1 if bool is true, proc2 if bool is false
init incr limit proc		for	-	execute proc with values from init by steps of incr to limit
int proc		repeat	-	execute proc int times
proc		loop	-	execute proc an indefinite number of times
-		exit	-	exit innermost active loop
-		stop	-	terminate stopped context
any		stopped	bool	establish context for catching stop
-		countexecstack	int	count elements on exec stack
array		execstack	subarray	copy exec stack into array
-		quit	-	terminate interpreter
-		start	-	executed at interpreter startup
Type, Attribute, and Conversion Operators
any		type	name	return name identifying the type of any
any		cvlit	any	make object be literal
any		cvx	any	make object be executable
any		xcheck	bool	test executable attribute
array | packedarray | file | string		executeonly	array | packedarray | file | string	reduce access to execute-only
array | packedarray | dict | file | string		noaccess	array | packedarray | dict | file | string	disallow any access
array | packedarray | dict | file | string		readonly	array | packedarray | dict | file | string	reduce access to read-only
array | packedarray | dict | file | string		rcheck	bool	test read access
array | packedarray | dict | file | string		wcheck	bool	test write access
num | string		cvi	int	convert to integer
string		cvn	name	convert to name
num | string		cvr	real	convert to real
num radix string		cvrs	substring	convert to string with radix
any string		cvs	substring	convert to string
File Operators
string1 string2		file	file	open file identified by string1 with access string2
src | tgt param1 ... paramn name		filter	file	establish filtered file
file		closefile	-	close file
file		read	int true or false	read one character from file
file int		write	-	write one character to file
file string		readhexstring	substring bool	read hex from file into string
file string		writehexstring	-	write string to file as hex
file string		readstring	substring bool	read string from file
file string		writestring	-	write string to file
file string		readline	substring bool	read line from file into string
file		token	token true or false	read token from file
file		bytesavailable	int	number of bytes available to read
-		flush	-	send buffered data to standard output file
file		flushfile	-	send buffered data or read to EOF
file		resetfile	-	discard buffered characters
file		status	bool	return status of file
string		status	pages bytes referenced created true or false	return information about named file
string		run	-	execute contents of named file
-		currentfile	file	return file currently being executed
string		deletefile	-	delete named file
string1 string2		renamefile	-	rename file string1 to string2
template proc scratch		filenameforall	-	execute proc for each file name matching template
file int		setfileposition	-	set file to specified position
file		fileposition	int	return current position in file
string		print	-	write string to standard output file
any		=	-	write text representation of any to standard output file
any		==	-	write syntactic representation of any to standard output file
|- any1 ... anyn		stack	|- any1 ... anyn	print stack non-destructively using =
|- any1 ... anyn		pstack	|- any1 ... anyn	print stack non-destructively using ==
obj int		printobject	-	write binary object to standard output file, using int as tag
file obj int		writeobject	-	write binary object to file, using int as tag
int		setobjectformat	-	set binary object format (0 = disable, 1 = IEEE high, 2 = low, 3 = native high, 4 = low)
-		currentobjectformat	int	return binary object format
Resource Operators
key instance category		defineresource	instance	register named resource instance in category
key category		undefineresource	-	remove resource registration
key category		findresource	instance	return resource instance identified by key in category
key category		resourcestatus	status size true or false	return status of resource instance
template proc scratch category		resourceforall	-	enumerate resource instances in category
Virtual Memory Operators
-		save	save	create VM snapshot
save		restore	-	restore VM snapshot
bool		setglobal	-	set VM allocation mode (false = local, true = global)
-		currentglobal	bool	return current VM allocation mode
any		gcheck	bool	true if any is simple or in global VM, false if in local VM
bool1 password		startjob	bool2	start new job that will alter initial VM if bool1 is true
index any		defineuserobject	-	define user object associated with index
index		execuserobject	-	execute user object associated with index
index		undefineuserobject	-	remove user object associated with index
-		UserObjects	array	current UserObjects array defined in userdict
Miscellaneous Operators
proc		bind	proc	replace operator names in proc by operators
-		null	null	push null on operand stack
-		version	string	interpreter version
-		realtime	int	return real time in milliseconds
-		usertime	int	return execution time in milliseconds
-		languagelevel	int	level of language features
-		product	string	product name
-		revision	int	product revision level
-		serialnumber	int	machine serial number
-		executive	-	invoke interactive executive
bool		echo	-	turn on/off echoing
-		prompt	-	executed when ready for interactive input
Graphics State Operators - Device Independent
-		gsave	-	push graphics state
-		grestore	-	pop graphics state
-		grestoreall	-	pop to bottommost graphics state
-		initgraphics	-	reset graphics state parameters
-		gstate	gstate	create graphics state object
gstate		setgstate	-	set graphics state from gstate
gstate		currentgstate	gstate	copy current graphics state into gstate
num		setlinewidth	-	set line width
-		currentlinewidth	num	return current line width
int		setlinecap	-	set shape of line ends for stroke (0 = butt, 1 = round, 2 = square)
-		currentlinecap	int	return current line cap
int		setlinejoin	-	set shape of corners for stroke (0 = miter, 1 = round, 2 = bevel)
-		currentlinejoin	int	return current line join
num		setmiterlimit	-	set miter length limit
-		currentmiterlimit	num	return current miter limit
bool		setstrokeadjust	-	set stroke adjust (false = disable, true = enable)
-		currentstrokeadjust	bool	return current stroke adjust
array offset		setdash	-	set dash pattern for stroking
-		currentdash	array offset	return current dash pattern
array		setcolorspace	-	set color space
-		currentcolorspace	array	return current color space
comp1 ... compn		setcolor	-	set color components
-		currentcolor	comp1 ... compn	return current color components
num		setgray	-	set color space to DeviceGray and color to specified gray value (0 = black, 1 = white)
-		currentgray	num	return current color as gray value
hue sat brt		sethsbcolor	-	set color space to DeviceRGB and color to specified hue, saturation, brightness
-		currenthsbcolor	hue sat brt	return current color as hue, saturation, brightness
red green blue		setrgbcolor	-	set color space to DeviceRGB and color to specified red, green, blue
-		currentrgbcolor	red green blue	return current color as red, green, blue
cyan magenta yellow black		setcmykcolor	-	set color space to DeviceCMYK and color to specified cyan, magenta, yellow, black
-		currentcmykcolor	cyan magenta yellow black	return current color as cyan, magenta, yellow, black
Graphics State Operators - Device Dependent
dict		sethalftone	-	set halftone dictionary
-		currenthalftone	dict	return current halftone dictionary
frequency angle proc		setscreen	-	set gray halftone screen
-		currentscreen	frequency angle proc	return current gray halftone screen
redfreq redang redproc greenfreq greenang greenproc bluefreq blueang blueproc grayfreq grayang grayproc		setcolorscreen	-	set all four halftone screens
-		currentcolorscreen	redfreq redang redproc greenfreq greenang greenproc bluefreq blueang blueproc grayfreq grayang grayproc	return all four halftone screens
proc		settransfer	-	set gray transfer function
-		currenttransfer	proc	return current gray transfer function
redproc greenproc blueproc grayproc		setcolortransfer	-	set all four transfer functions
-		currentcolortransfer	redproc greenproc blueproc grayproc	return current transfer functions
proc		setblackgeneration	-	set black generation function
-		currentblackgeneration	proc	return current black generation function
proc		setundercolorremoval	-	set undercolor removal function
-		currentundercolorremoval	proc	return current undercolor removal function
dict		setcolorrendering	-	set CIE based color rendering dictionary
-		currentcolorrendering	dict	return current CIE based color rendering dictionary
num		setflat	-	set flatness tolerance
-		currentflat	num	return current flatness
bool		setoverprint	-	set overprint parameter
-		currentoverprint	bool	return current overprint parameter
Coordinate System and Matrix Operators
-		matrix	matrix	create identity matrix
-		initmatrix	-	set CTM to device default
matrix		identmatrix	matrix	fill matrix with identity transform
matrix		defaultmatrix	matrix	fill matrix with device default matrix
matrix		currentmatrix	matrix	fill matrix with CTM
matrix		setmatrix	-	replace CTM by matrix
tx ty		translate	-	translate user space by (tx ty)
tx ty matrix		translate	matrix	define translation by (tx ty)
sx sy		scale	-	scale user space by sx and sy
sx sy matrix		scale	matrix	define scaling by sx and sy
angle		rotate	-	rotate user space by angle degrees
angle matrix		rotate	matrix	define rotation by angle degrees
matrix		concat	-	replace CTM by matrix x CTM
matrix1 matrix2 matrix3		concatmatrix	matrix3	fill matrix3 with matrix1 x matrix2
x y		transform	x' y'	transform (x, y) by CTM
x y matrix		transform	x' y'	transform (x, y) by matrix
dx dy		dtransform	dx' dy'	transform distance (dx, dy) by CTM
dx dy matrix		dtransform	dx' dy'	transform distance (dx, dy) by matrix
x' y'		itransform	x y	inverse transform (x', y') by CTM
x' y' matrix		itransform	x y	inverse transform (x', y') by matrix
dx' dy'		idtransform	dx dy	inverse transform distance (dx', dy') by CTM
dx' dy' matrix		idtransform	dx dy	inverse transform distance (dx', dy') by matrix
matrix1 matrix2		invertmatrix	matrix2	fill matrix2 with inverse of matrix1
Path Construction Operators
-		newpath	-	initialize current path to be empty
-		currentpoint	x y	return current point coordinate
x y		moveto	-	set current point to (x, y)
dx dy		rmoveto	-	relative moveto
x y		lineto	-	append straight line to (x, y)
dx dy		rlineto	-	relative lineto
x y r ang1 ang2		arc	-	append counterclockwise arc
x y r ang1 ang2		arcn	-	append clockwise arc
x1 y1 x2 y2 r		arct	-	append tangent arc
x1 y1 x2 y2 r		arcto	xt1 yt1 xt2 yt2	append tangent arc
x1 y1 x2 y2 x3 y3		curveto	-	append Bezier cubic section
dx1 dy1 dx2 dy2 dx3 dy3		rcurveto	-	relative curveto
-		closepath	-	connect subpath back to its starting point
-		flattenpath	-	convert curves to sequences of straight lines
-		reversepath	-	reverse direction of current path
-		strokepath	-	compute outline of stroked path
userpath		ustrokepath	-	compute outline of stroked userpath
serpath matrix		ustrokepath	-	compute outline of stroked userpath
string bool		charpath	-	append character outline to current path
userpath		uappend	-	interpret userpath and append to current path
-		clippath	-	set current path to clipping path
llx lly urx ury		setbbox	-	set bounding box for current path
-		pathbbox	llx lly urx ury	return bounding box of current path
move line curve close		pathforall	-	enumerate current path
bool		upath	userpath	create userpath for current path; include ucache if bool is true
-		initclip	-	set clipping path to device default
-		clip	-	clip using non-zero winding number rule
-		eoclip	-	clip using even-odd inside rule
x y width height		rectclip	-	clip with rectangular path
numarray | numstring		rectclip	-	clip with rectangular paths
-		ucache	-	declare that user path is to be cached
Painting Operators
-		erasepage	-	paint current page white
-		fill	-	fill current path with current color
-		eofill	-	fill using even-odd rule
-		stroke	-	draw line along current path
userpath		ufill	-	interpret and fill userpath
userpath		ueofill	-	fill userpath using even-odd rule
userpath		ustroke	-	interpret and stroke userpath
userpath matrix		ustroke	-	interpret userpath, concatenate matrix, and stroke
x y width height		rectfill	-	fill rectangular path
numarray | numstring		rectfill	-	fill rectangular paths
x y width height		rectstroke	-	stroke rectangular path
numarray | numstring		rectstroke	-	stroke rectangular paths
dict		image	-	paint any sampled image
width height bits/samp matrix datasrc		image	-	paint monochrome sampled image
width height bits/comp matrix datasrc0 ... datasrcn-1 multi ncomp		colorimage	-	paint color sampled image
dict		imagemask	-	paint current color through mask
width height polarity matrix datasrc		imagemask	-	paint current color through mask
Insideness Testing Operators
x y		infill	boot	test whether point (x, y) would be painted by fill
userpath		infill	bool	test whether pixels in userpath would be painted by fill
x y		ineofill	bool	test whether point (x, y) would be painted by eofill
userpath		ineofill	bool	test whether pixels in userpath would be painted by eofill
x y userpath		inufill	bool	test whether point (x, y) would be painted by ufill of userpath
userpath1 userpath2		inufill	bool	test whether pixels in userpath1 would be painted by inufill of userpath2
x y userpath		inueofill	bool	test whether point (x, y) would be painted by ueofill of userpath
userpath1 userpath2		inueofill	bool	test whether pixels in userpath1 would be painted by ueofill of userpath2
x y		instroke	bool	test whether point (x, y) would be painted by stroke
x y userpath		inustroke	bool	test whether point (x, y) would be painted by ustroke of userpath
x y userpath matrix		inustroke	bool	test whether point (x, y) would be painted by ustroke of userpath
userpath1 userpath2		inustroke	bool	test whether pixels in userpath1 would be painted by ustroke of userpath2
userpath1 userpath2 matrix		inustroke	bool	test whether pixels in userpath1 would be painted by ustroke of userpath2
Form and Pattern Operators
pattern matrix		makepattern	pattern'	create pattern instance from prototype
comp1 ... compn pattern		setpattern	-	install pattern as current color
form		execform	-	paint form
Device Setup and Output Operators
-		showpage	-	transmit and reset current page
-		copypage	-	transmit current page
dict		setpagedevice	-	install page-oriented output device
-		currentpagedevice	dict	return current page device parameters
-		nulldevice	-	install no-output device
Character and Font Operators
key font		definefont	font	register font as a font dictionary
key		undefinefont	-	remove font registration
key		findfont	font	return font dictionary identified by key
font scale		scalefont	font'	scale font by scale to produce new font'
font matrix		makefont	font'	transform font by matrix to produce new font'
font		setfont	-	set font dictionary in graphics state
-		currentfont	font	return current font dictionary
-		rootfont	font	return root composite font dictionary
key scale | matrix		selectfont	-	set font dictionary given name and transform
string		show	-	paint characters of string on page
ax ay string		ashow	-	add (ax ay) to width of each character while showing string
cx cy char string		widthshow	-	add (cx cy) to width of char while showing string
cx cy char ax ay string		awidthshow	-	combine effects of ashow and widthshow
string numarray | numstring		xshow	-	paint characters of string using x widths in numarray | numstring
string numarray | numstring		xyshow	-	paint characters of string using x and y widths in numarray | numstring
string numarray | numstring		yshow	-	paint characters of string using y widths in numarray | numstring
name		glyphshow	-	paint character identified by name
string		stringwidth	wx wy	width of string in current font
proc string		cshow	-	invoke show mapping algorithm and call proc
proc string		kshow	-	execute proc between characters shown from string
-		FontDirectory	dict	dictionary of font dictionaries
-		GlobalFontDirectory	dict	dictionary of font dictionaries in global VM
-		StandardEncoding	array	Adobe standard font encoding vector
-		ISOLatin1Encoding	array	international ISO Latin-1 font encoding vector
key		findencoding	array	find encoding array
wx wy llx lly urx ury		setcachedevice	-	declare cached character metrics
w0x w0y llx lly urx ury w1x w1y vx vy		setcachedevice2	-	declare cached character metrics
wx wy		setcharwidth	-	declare uncached character metrics
Interpreter Parameter Operators
dict		setsystemparams	-	set system-wide interpreter parameters
-		currentsystemparams	dict	return system-wide interpreter parameters
dict		setuserparams	-	set per-context interpreter parameters
-		currentuserparams	dict	return per-context interpreter parameters
string dict		setdevparams	-	set parameters for input/output device
string		currentdevparams	dict	return device parameters
int		vmreclaim	-	control garbage collector
int		setvmthreshold	-	control garbage collector
-		vmstatus	level used maximum	report VM status
-		cachestatus	bsize bmax msize mmax csize cmax blimit	return font cache status and parameters
num		setcachelimit	-	set maximum bytes in cached character
mark size lower upper		setcacheparams	-	change font cache parameters
-		currentcacheparams	mark size lower upper	return current font cache parameters
mark blimit		setucacheparams	-	set user path cache parameters
-		ucachestatus	mark bsize bmax rsize rmax blimit	return user path cache status and parameters
Display PostScript Operators
-		currentcontext	context	return current context identifier
mark obj1 ... objn proc		fork	context	create context executing proc with obj1 ... objn as operands
context		join	mark obj1 ... objn	await context termination and return its results
context		detach	-	enable context to terminate immediately when done
-		lock	lock	create lock object
lock proc		monitor	-	execute proc while holding lock
-		condition	condition	create condition object
lock condition		wait	-	release lock, wait for condition, reacquire lock
condition		notify	-	resume contexts waiting for condition
-		yield	-	suspend current context momentarily
index name		defineusername	-	define encoded name index
-		viewclip	-	set view clip from current path
-		eoviewclip	-	set view clip using even-odd rule
x y width height		rectviewclip	-	set rectangular view clipping path
numarray | numstring		rectviewclip	-	set rectangular view clipping paths
-		initviewclip	-	reset view clip
-		viewclippath	-	set current path from view clip
-		deviceinfo	dict	return dictionary containing information about current device
-		wtranslation	x y	return translation from window origin to device space origin
x y		sethalftonephase	-	set halftone phase
-		currenthalftonephase	x y	return current halftone phase
Errors
		configurationerror		setpagedevice request cannot be satisfied
		dictfull		no more room in dictionary
		dictstackoverflow		too many begins
		dictstackunderflow		too many ends
		execstackoverflow		exec nesting too deep
		handleerror		called to report error information
		interrupt		external interrupt request (e.g., Control-C)
		invalidaccess		attempt to violate access attribute
		invalidcontext		improper use of context operation
		invalidexit		exit not in loop
		invalidfileaccess		unacceptable access string
		invalidfont		invalid font name or dictionary
		invalidid		invalid identifier for external object
		invalidrestore		improper restore
		ioerror		input/output error occurred
		limitcheck		implementation limit exceeded
		nocurrentpoint		current point is undefined
		rangecheck		operand out of bounds
		stackoverflow		operand stack overflow
		stackunderflow		operand stack underflow
		syntaxerror		PostScript language syntax error
		timeout		time limit exceeded
		typecheck		operand of wrong type
		undefined		name not known
		undefinedfilename		file not found
		undefinedresource		resource instance not found
		undefinedresult		over/underflow or meaningless result
		unmatchedmark		expected mark not on stack
		unregistered		internal error
		VMerror		VM exhausted