%RECINDEX_BASE()% function
Retrieves each CSV records index of upload unit. A concept of upload unit is described at this page.
This function provides verry similer function of %RECINDEX% property, but this function can set offset to index with argument.
If you assign 0 for the argument, the result is as same as %RECINDEX% property.
This function is valid for request parameter name, request parameter value, CSV column name, CSV column value and success string at CSV upload.
Return valuevalue type 
1st arg.integer typeoffset value for record index.
%RECINDEX_BASE(1)%