This option is similar to the Expression Precision/Scale option. The Progress 4GL database engine allows the storage of character strings which are longer than the declared SQL width. For instance, creating a table with a char column will default to 8 but Progress will allow you to specify more than 8 characters. By specifying a Max value, with this option, the ODBC driver internally will override the value provided by the ODBC call SQLDescribecol and use the value provided.
This document is empty and basically useless. It is generated by a web service that can make some statements in HTML Microdata format. This time the service made zero such statements, sorry.