One value computed by a typed formula, such as wall * 2 + max(gap, 1 mm). Every name in the formula is an input of the block with that name: a number or a vector, typed or wired, one value or a field. The formula takes + - * / and ^ (a power), brackets, the math functions (sqrt, clamp, floor, sin, dot, cross, …; the Help tab lists them), the constants pi, tau, e and phi, and numbers with a unit (5 mm, 30°, 2 MPa). Units go through the arithmetic: mm times mm is mm², a number without a unit takes the unit of what it meets, two values that must share a unit and do not are refused, and a root or a power that would lose a unit (the square root of mm) is refused. An angle given as a number is in degrees. A field (or a vector field) counts as a length in mm where it is added to, subtracted from or compared with a value that has a unit; in a product, a quotient or a function it has no fixed unit and takes the unit of what it meets, like a number without one; inside sin, cos and tan it is read in radians. Two vectors add and subtract; a number scales a vector; dot(a, b) and cross(a, b) multiply two vectors. A list at an input runs the formula once per item. A name the formula no longer reads but the block still holds a value for is marked as not used.
The formula. Every name in it is an input of this block.
Values the block gives besides its output. The editor lists them under Properties, and an input can read one by reference.
The field read as a Solid whose surface is where the field is zero.
The box the field is evaluated in.
The field with its sign flipped (−f), which swaps inside and outside.
The field divided by its gradient length (f/|∇f|) so it reads close to a true distance; the zero set does not move.