Imperative DIM (an enhanced DIM)

This BASIC allows a DIM statement to have numeric expressions in the bound arguments, which is not allowed in the Full BASIC standard.
Example.
`DIM A(N),B(2*N)`
When a numeric expression except a constant is written as the bound argument, no array elements are arranged until the DIM statement is executed.
If a size of greater than 0 has been assigned once, the size can not be enlarged hereafter.
Note.
An enhanced DIM statement has both features of declarative and imperative.
No internal procedure can include this type of DIM statements.