String MAT Statements

Let A$ and B$ be string arrays.
`MAT A$=nul$`
assigns the empty string to all elements of A$
Let s$ be a string expression.
`MAT A$=(s$) & nul$`
assigns s$ to all elements of A$
When s$ is a string variable, a string constant, or a string function reference, the parentheses can be omitted.
`MAT A$(m:n)=(s$) & nul$`
replace the m-th character to the n-th character of A$ with s$.
Le A$ be 1-dimensional and the lower bound of it be equal to option base.
`MAT A$=nul$(n)`
changes the upper bound of A$ to n, and assigns the empty string to all elements.
Le A$ be 2-dimensional and the lower bounds of it be equal to option base.
`MAT A$=nul$(m,n)`
changes the upper bounds of A$ to m and n, and assigns the empty string to all elements.
Let A$ and B$ have the same dimension and the same lower bounds.
`MAT A$=B$`
substitutes B$ for A$.
Let A$ and B$ have the same size.
`MAT A$(m:n)=B$`
Replace the m-th character to n-th character of A$ with B$.
Let B$ and C$ have the same size and the same dimension as A$.
MAT `A$=B$ & C$`
Substitutes an array that is obtained by concatenating each element of B$ and each element of C$ for A$.
Let A$ and B$ have the same dimension, s$ be a string expression.
`MAT A$=(s$) & B$`
Substitutes an array that is obtained by concatenating s$ and each element of B$ for A$.
`MAT A$=B$ & (s$)`
Substitutes an array that is obtained by concatenating each element of B$ and s$ for A$.