Each equation may therefore cover several lines. Y is just for readability. The equations describing the algebraic variables have to precede the differential equations. Preferably an algebraic variable should be defined before it is used in another equation. The names of variables, algebraic variables, and parameters should be less than eight characters long.
Names start with a letter.
The other six characters by be any combination of letters and digits. Numbers in equations, e.g., 3.141592654, should be shorter than 11 characters, i.e., 3.14159265. Standard Fortran functions with one or two arguments are all allowed.