My very old HL7 parser has just hit a snag as it is now getting some messages with a ZDS segment present. It was easy to fix by adding a ZDS object to my parser, but I am trying to find out what it is used for. Googling hasn't helped much. This is a sample

```
ZDS|PERFORM|p0001236^PATEL^ATEST^^^^^^HHB_INOP_PRSNL^^^^OTHER|20100714101800|CD:653
ZDS|TRANSCRIBE|p0001236^PATEL^ATEST^^^^^^HHB_INOP_PRSNL^^^^OTHER|20100714101800|CD:653
ZDS|SIGN|p0001236^PATEL^ATEST^^^^^^HHB_INOP_PRSNL^^^^OTHER|20100714101912|CD:653

```

So, I'm interested in what each field is though looking at this sample data, it seems I don't lose much by just dropping the whole segment.