Instructions are separeted by space, [....] is used for a list.
Lower-case letters are changed in upper-case. so you can write FW, fw, Fw or fW  ... 

Primitives defined:

PD : Pencil is down and turtle move and draw
PU : Pencil is down and turtle move without drawing
HT : Hide turtle
ST : Show turtle
CLEAN : All drawing are erased and turtle stay in current position
CS : All drawing are erased and turtle is in initial position and heading

Moving turtle

FD n : Turtle go forward of n in current direction
BK n : Turtle go backward of n in current direction
RT n : Turtle turn on right of n degree
LT n : Turtle turn on left of n degree

Procedures

REPEAT n [..... instructions ... ] : repeat n times instructions in [..... ]
TO name  ... instructions ... END : create procedure with name and variables 

Example:
TO SQUARE REPEAT 4 [FD 100 RT 90] END  create procedure SQUARE
If you write SQUARE, a square with 100 for side will be drawed at position of turtle and account consideration of heading.

A procedure can be used in definition another, if SQUARE is defined, you can create:
TO DRAWING REPEAT 8 [RT 45 SQUARE] END
Writing DRAWING, you get 8 squares with same vertice and turning of 45° one after one.

Variables

:Name_variable : This variable is defined with a procedure or with GIVE.

Example:
TO SQUARE :DIM :ANGLE RT :ANGLE REPEAT 4 [FD :DIM RT 90] END create procedure SQUARE
If you write SQUARE 50 45, turtle turn of 45° on right and draw a square with 50 for side.

MAKE "Name_variable value: Variable get value, this value can be number or other variable with operations. Example if :X has 100 as value MAKE "Y :X / 2 create :Y with 50 as value.

Conditional execution

IF condition [instructions if true] [instructions if false] :

Operators

+ - * / : This 4 operations are defined on numbers or variables.