Flow : DLC ------> NODE
| Field | Type | Description | 
|---|---|---|
| nxtqptr | PTRBFHDR | Pointer to next buffer header in a queue | 
| hdreptr | PTRBFELT | Pointer to first buffer element | 
| numelts | CHAR | Number of buffer elements: 1 | 
| msgtype | CHAR | Message type: OPENMSG (0x01) | 
| srcl | CHAR | Source locality | 
| srcp | CHAR | Source partner | 
| srci | INTEGER | Source index | 
| destl | CHAR | Destination locality | 
| destp | CHAR | Destination partner | 
| desti | INTEGER | Destination index | 
| ophdr.openqual | CHAR | Open qualifier - RSPOK (0x02) - RSPERR (0x03) | 
| ophdr.opentype | CHAR | Open type - LINK (0x10) | 
| ophdr.opresid | INTEGER | Resource identifier | 
| ophdr.operr1 | INTEGER | Error code (see below) | 
| ophdr.operr2 | INTEGER | Reserved | 
| hdreptr–>elteptr | PTRBFELT | Pointer to next buffer element: NULL | 
| hdreptr–>startd | INTEGER | Index to start of data in this buffer element's data array: 1 | 
| hdreptr–>endd | INTEGER | Index to last byte of data in this buffer element's data array | 
| hdreptr–>dataru | CHAR[SNANBEDA] | Defined as follows, where s = startd–1 | 
| dataru[s..s+9] | Source name—same as destination name from Open(LINK) Request | |
| dataru[s+10..s+19] | Destination name—name of local node; same as source name from Open(LINK) Request | |
| dataru[s+22..s+23] | Maximum BTU size supported by SNALink | 
The error codes (for an ERROR-RESPONSE) are defined as follows in SNA_CNST.H:
| Symbolic constant | Value | Description | 
|---|---|---|
| ERINIFAIL | 0x01 | Hardware initialization failed | 
| ERINVXID | 0x08 | Invalid XID length | 
| ERLINKOPN | 0x09 | Link already open | 
| ERLLCERR | 0x0A | LCC error; fatal hardware failure | 
| ERBADINDX | 0x0B | Invalid link index | 
| ERBADOPN | 0x0C | Open(LINK) has insufficient data | 
| ERCONNTO | 0x0D | Link connection time-out | 
| ERNORES | 0x0E | Maximum connection count reached –or– No more internal control blocks | 
| EROPNPND | 0x11 | Close(LINK) arrived while Open(LINK) pending | 
| ERDUPREQ | 0x12 | Duplicate request |