STEP n — set step scale
FORWARD n / BACK n — move along heading
LEFT n / RIGHT n — strafe perpendicular
TURN a — rotate heading by a°
SETHEADING a — set absolute heading (0=right)
PENUP / PENDOWN — lift / lower pen
CENTER — jump pen to canvas centre
GOTO x y — absolute (canvas-centre origin)
GOTO +dx +dy — relative move (prefix + or −)
ARC r a — true geometric arc, radius r, sweep a°
POP r n — Spherepop radial burst: n petals on radius r
REPEAT n { … } — repeat block (nestable)
CURVE t s e dt { X expr · Y expr } — parametric
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