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• StrExpr$ is a string expression
• Position% is the starting position of the substring 
• Length% is an optional integer value containing the number of characters for the substring to contain

Remarks

1. NullString is NullString is considered as a DETERMINED empty string 
2. If Length% is omitted, the full remaining part of the string is adopted.

Examples

MID$("NullString", 3, 1) returns "NullString"

MID$("Qnowledge Wageningen", 8, 6) returns "ge Wag"

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