Movement of the turtle; pen and colour settings

This first table sets out the primitives which govern the movement of the turtle.

Primitives	Arguments	Use
`forward`, `fd`	n : number of steps	Moves the turtle forward n steps in the direction it is currently facing.
`back`, `bk`	n: number of steps	Moves the turtle backwards n steps in the direction it is currently facing.
`right`, `rt`	n: angle	Turns the turtle n degrees towards the right in relation to the direction it is currently facing.
`left`, `lt`	n: angle	Turns the turtle n degrees towards the right in relation to the direction it is currently facing.
`circle`	R: number	Draws a circle of R radius around the turtle.
`arc`	R cap1 cap2: numbers	Draws an arc of R radius around the turtle. This arc is inscribed between the caps cap1 and cap2.
`home`	any	Returns the turtle to its initial position, that is, the co-ordinates [0 0] with a heading of 0 degrees.
`setpos, setposition`	[x y]: list of two nunbers	Moves the turtle to the co-ordinates specified by the two numbers in the list (x specifies the x-axis and y the y-axis)
`setx`	x: x-axis	Moves the turtle horizontally to the point x on the x-axis
`sety`	y: y-axis	Moves the turtle vertically to the point y on the y-axis
`setxy`	x y: x-co-ordinate followed by y-co-ordinate	Identical to setpos [x y]
`setheading, seth`	n: heading or bearing	Orients the turtle in the specified direction. 0 corresponds to a position facing vertically upwards. The heading when the turtle is rotated is then based on compass bearings.
`label`	a: word or list	Draw the specified word or list at the turtle's location, and following the direction it is facing. Eg: `label [Hello there!]` will write the sentence "Hello there!" wherever the turtle is, and corresponding to its bearing or heading.
`labellength`	a: word or list	Returns the length that needs the word or the list to be displayed on the screen with the primitive `label` using the current font.
`dot`	a: list	The point defined by the co-ordinates in the list will be highlighted (in the pen colour).

Primitives	Arguments	Use
`showturtle`, `st`	none	Makes the turtle visible on the screen.
`hideturtle`, `ht`	none	Makes the turtle invisible on the screen.
`clearscreen`, `cs`	none	Empties the drawing area.
`wash`	none	Erases the drawing area but leaves the turtle in the same place.
`resetall`	none	Initialize the XLogo interface to standard values (PenColor: black, ScreenColor:white, Animation mode: disabled, Text and Graphics Font: Dialog 12 pts, pen shape: square, Drawing quality: normal, turtles allowed: 16, mode trace: disabled, screen size [1000 1000]) and empties the drawing area.
`pendown`, `pd`	none	The turtle will draw a line when it moves.
`penup`, `pu`	none	The turtle will not draw a line when it moves.
`penerase`, `pe`	none	The turtle will rub out any marks that it meets.
`penreverse`, `px`	none	Lower the pen and put the turtle in inverted mode.
`penpaint`, `ppt`	none	Lower the pen and put the turtle in classic drawing mode.
`setpencolor`, `setpc`	a: whole number or list [r g b]	Sets the pen color. See p..
`setscreencolor`, `setsc`	a: whole number or list [r g b]	Sets the screen color. See p..
`pos, position`	none	Gives the current position of the turtle.Eg: `pos` returns [10 -100]
`heading`	none	Gives the bearing or heading of the turtle (cf `setheading`)
`towards`	a: list	The list must contain two numbers representing co-ordinates. Gives the heading which the turtle must follow to go towards the point defined by the co-ordinates in the list.
`distance`	a: list	The list must contain two numbers representing co-ordinates. Gives the number of steps between the current position and the point defined by the co-ordinates in the list.
`pencolor, pc`	a: list	Gives the current colour of the pen. This colour is specified by a list [r g b] where r is the red component, b the blue and g the green.
`screencolor, sc`	a: list	Gives the current colour of the screen (background). This colour is specified by a list [r g b] where r is the red component, b the blue and g the green.
`window`	none	The turtle can travel outside the drawing area (but of course, it cannot draw there).
`wrap`	none	If the turtle leaves the drawing area, it will reappear on the opposite side!
`fence`	none	The turtle is confined to the drawing area. If it is about to go outside, an error message will let you know, and give you the maximum number of steps the turtle can move before the exit point is reached (to within 1 or 2 steps ...).
`perspective`	None	The turtle can move through 3d Space. (See Special Section for this mode). To quit this mode, Use one of these primitives `window`, `wrap` or `fence`
`findcolor,fc`	a: list	Returns to the colour of the `a` coordinates pixel. This color is determined thanks to a [r g b] list where r is red, g is green and b is blue.
`setpenwidth`, `setpw`	n: number	Defines the thickness of the pen nib in pixels. The default is 1. The pen has a square nib. (Other shapes will be provided in future versions.)
`penwidth`, `pw`	none	Returns the thickness of the pen nib in pixels.
`setPenShape, setps`	0 or 1	set the pen shape. 0 $\to$ square. 1 $\to$ oval
`penshape, ps`	none	returns the pen shape. 0 $\to$ square. 1 $\to$ oval
`setdq, setDrawingQuality`	0 or 1 or 2	set the drawing Quality 0 $\to$ normal. 1 $\to$ high. 2 $\to$ Low
`dq, DrawingQuality`	none	returns the drawing Quality 0 $\to$ normal. 1 $\to$ high. 2 $\to$ Low
`setscreensize`	[width height]	Set the screen size to the dimension contained in the list. `setscreensize [1000 1000]`
`screensize`	list	Returns the current screen size in a list. `setscreensize [1000 1000]`
`setshape`	n: number	You can choose your preferred turtle with the second tab of menu Options-Preferences.... But you can choose your favourite turtle with `setshape`. The number n goes from 0 to 6. (0 is the triangular shape).
`shape`	none	Returns the number that represents the shape of the turtle.
`setfontsize`, `setfs`	n: number	When you write on the screen with the primitive `label`, it's possible to modify the size of the font with `setfontsize`. The size of the font is 12 by default.
`fontsize`	none	Returns the size of the font when you write on the screen with the primitive `label`.
`setfn`, `setfontname`	n: number	Select the font number when you write on the screen with the primitive `label`. You can find the link between number and font in Menu $\to$ OptionsvPreferences $\to$ Tab Font.
`fontname`	none	Returns a list with two elements. The first is the number corresponding to the font used when you write on the screen with the primitive `label`. The last element is a list which contains the name of the font.
`setseparation, setsep`	a: number	Determines the ratio between the graphic screen and the history zone. The number a must be included between 0 and 1. When a equals 1 the drawing zone uses all the space, when a equals 0, the history zone uses all the window.
`separation`, `sep`	none	Provides the current ratio between the drawing zone and the history zone.
`grid`	a, b integer	Draw a grid. Each square has dimension a and b.
`stopgrid`	none	Erase grid.
`setgridcolor`	Color	Allow the user to choose a custom color for the grid. Eg: `setgridcolor red`
`gridcolor`	none	Return current grid color.
`grid?`	none	Return true if the grid is drawn, else return false.
`axis`	n: integer	Draw horizontal and vertical axis. The distance between two divisions is steps.
`xaxis`	n: integer	Draw only horizontal axis. The distance between two divisions is steps.
`yaxis`	n: integer	Draw only vertical axis. The distance between two divisions is steps.
`stopaxis`	none	Erase both axis.
`setaxiscolor`	Color	Allow the user to choose a custom color for the axis. Eg: `setaxiscolor green`
`axiscolor`	none	Return current axis color.
`xaxis?`	none	Return true if the horizontal axis is drawn, else return false.
`yaxis?`	none	Return true if the vertical axis is drawn, else return false.
`zoom`	a	Zoom on the drawing screen. In fact, the number `a` represents the scale regarding to the original image size fixed in the preference panel.
`zonesize`	none	Returns a list which contains four numbers. These integers are the coordinates of the left upper corner of the drawing zone and the coordinates for the right bottom corner.
`message, msg`	a: list	Shows the message in list in a dialog box, the program stops until the user has clicked the button "OK"