Epson POS打印机 - 自动状态返回规格

I'm trying interpret the Automatic Status Back (ASB) data from Epson POS printer. I've successfully made contact with the printer using some example code from the UB-E20 Technical Reference Guide (www.amigopos.com/faq/faq_262.aspx). Unfortunately, the manual only states where I can expect the 4 bytes of ASB data in the return string from my query. It does not explain what each bits represents in those 4 bytes. I can see that the return values change when I open the cover of the printer and/or remove paper, but I want to be certain that I am looking for the proper values for the different failure modes. I'm trying interpret the Automatic Status Back