---
task: Block / unblock an item and write to a blocked item
version: R1.05 (first written for R1.03)
source: IM 36K10G10-01EN 5th ed. (Feb. 2026) §3.3, §3.4; IM 36K10C10-01EN 5th ed. (Feb. 2026) §3.4, §3.5; practiced with CI-Eng-Sample 2026-09-30 (R1.03)
status: verified on R1.03 (2026-09-30); on R1.05 the BLOCKED fields of SECTION_DF, ITEM_DF and ITEM_VAL and the option bits are unchanged (checked 2026-10-08, read-only); blocking and writes to a blocked item not re-tested on the shared R1.05 test server, re-test awaits a decision (ISS-129)
---

# Block / unblock an item

A blocked item is not updated (e.g. during device maintenance). Blocking can be done per item,
sub-item or section; sub-items of a blocked item keep working. **Changes live behaviour:**
follow the user's chosen way of working.

Block (`BLOCKED` 1) or unblock (`BLOCKED` 0) with an update file and `dssqld -m`:

```
@FIELDS
NAME,BLOCKED

@ITEM_DF
"<Section>.<Tag>",1
```

```
dssqld -m block.qli -l block.qlo
```

(Engineering Module: right-click the item or section › *Block/Unblock*.)

## Behaviour (verified on R1.03 with `CI-Eng-Sample.TANK1.INFLOW`)

- Blocked: option flag `blk` appears in `itmval -g`; the status number is unchanged (stayed 9).
- `itmval -p -n <item> -v <value>` on a blocked item is **silently ignored** (exit code 0, no
  message, value unchanged); so is `dssqld -m` on `ITEM_VAL.ITEM_VALUE` (reports *Modified*, 0
  errors). Check `blk` in `itmval -g` before writing (`knowledge/issues.md` ISS-011). Add `-o` to overwrite:
  `itmval -p -n <item> -v <value> -o`.
- After unblocking, `blk` is gone but `ublk` (option bit 16, *updated blocked*) remains: the
  item was written by an application (`itmval -o`) while it was blocked (IM 36K10C10 §3.5,
  ISS-001).

R1.05: not re-tested (blocking changes live behaviour on the shared test server). Before
relying on the silent-ignore behaviour on R1.05, block a test item, write it without and with
`-o`, and check the value and the `blk` / `ublk` flags as above.