Differences in blob handling between PowerBuilder 8.03 and 12.6

I'm migrating an application from PowerBuilder 8.03 to PowerBuilder 12.6. The only thing that doesn't work correctly is a module which works with blob variables that contain string data. I've found three functions that give different results in versions 8.03 and 12.6:

• The len function returns 100 in 8.03 and 200 in 12.6. In both cases, the same 100-character string had been converted to a blob and stored in a blob variable, and the len function was performed on the blob variable.
• BlobMid returns a blob that converts to a 2-character string in 8.03, but only half that in 12.6. Specifically, 8.03 returned "vv" but 12.6 only returned "v".
• BlobEdit gives different results in the two versions.

I noticed that in PB 12 the BlobEdit function takes an additional, optional parameter to specify the encoding format for string values.

I have two questions:

First, what changed between version 8.03 and 12.6 that causes these differences? Second, is there a value for the encoding parameter that would make the BlobEdit function give the same result in 12.6 that it did in 8.03?

Thanks in advance.