Strings are actually arrays of characters. As such, they can be manipulated as vector/matrices.

Creation of strings can be achieved by direct declaration:
str1 = 'abcd'
str2 = 'efgh'
They can also be obtained by extraction or concatenation.
str3 = str1(2:3)
str3 is a string extracted from str1, made of 2 characters, bc.
str4 = [str1 str2]

str4 is a string obtained by concatenation and contains abcdefgh.

In addition, the OpenMatrix language includes a complete set of functions to manipulate strings. The functions are described in detail in the Strings chapter of the Reference Guide.