MapSubstring  - Script function
                The MapSubstring script function is used to map parts of any expression to a previously loaded mapping table. The mapping is case sensitive and non-iterative, and substrings are mapped from left to right.
Syntax:
MapSubstring('map_name', expression)
Return data type: string
Arguments:
| Argument | Description | 
|---|---|
| map_name | 
                                 The name of a mapping table previously read by a mapping load or a mapping select statement. The name must be enclosed by single straight quotation marks.  | 
                        
| expression | The expression whose result is to be mapped by substrings. | 
Example:
In this example we load a list of product models. Each model has a set of attributes that are described by a composite code. Using the mapping table with MapSubstring, we can expand the attribute codes to a description.
The resulting table looks like this:
| Model | Description | 
|---|---|
| Twixie | Red Cotton Small | 
| Boomer | Blue Polyester Large | 
| Raven | Yellow Polyester Medium | 
| Seedling | Red Cotton Large | 
| SeedlingPlus | Red Cotton Large with hood | 
| Younger | Blue Cotton with patch | 
| MultiStripe | Red Yellow Blue Cotton Small/Medium/Large |