What the PDETextGetText method writes to textBuffer

The Help API says that the PDETextGetText method (PDEText pdeText, ASUns32 flags, ASInt32 index, ASUns8 * textBuffer) gets the text for a text run or character.
textBuffer - the text of the specified character or text run.

I created a PDF file in which I placed the text: abc.

I put the following statements in the code:
ASUns8 buffer [128];
PDETextGetText (pdeText, kPDETextRun, 0, buffer);
The debugger showed that the contents of the first 3 bytes of the buffer are '\ x1', '\ x2', '\ x1'. What then is written in buffer and why does it not match the text from the file?