Element or command attributes

In arithmetic expressions the attributes of physical elements or commands can occur as operands. They are named respectively by

element-name->attribute-name
command-name->attribute-name

If they are arrays, they are denoted by

element-name->attribute-name[index]
command-name->attribute-name[index]

Values are assigned to attributes in element definitions or commands.

Example:

D1:DRIFT,L=1.0;
D2:DRIFT,L=2.0-D1->L;

D1->L refers to the length L of the drift space D1.