# `HL7v2.Validation.FieldRules`
[🔗](https://github.com/Balneario-de-Cofrentes/hl7v2/blob/v3.10.1/lib/hl7v2/validation/field_rules.ex#L1)

Field-level validation rules for HL7v2 typed segments.

For each typed segment struct, checks:
- Required fields (`:r` optionality) are not nil
- Repeating fields with bounded `max_reps` do not exceed the limit
- Coded fields against HL7-defined tables (opt-in via `validate_tables: true`)

# `check`

```elixir
@spec check(
  struct() | {binary(), list()},
  keyword()
) :: [map()]
```

Returns a list of field-level validation errors/warnings for a single segment.

Skips validation for:
- `HL7v2.Segment.ZXX` (site-defined, no typed fields)
- Raw tuples `{name, fields}` (not typed)

## Options

- `:validate_tables` -- when `true`, checks coded fields against HL7 tables.
  Defaults to `false`.

# `conditional_errors`

```elixir
@spec conditional_errors(struct(), String.t(), atom(), map()) :: [map()]
```

Returns a list of conditional-rule errors/warnings for a segment.

Conditional rules are HL7-specified dependencies between fields. In strict
mode they produce `:error`, in lenient mode `:warning`.

An optional `context` map may contain `:trigger_event` and `:message_code`
extracted from MSH-9. When provided, trigger-aware rules (e.g., scheduling
modification segments, PV2 transfer events) use definitive checks instead
of heuristic approximations.

## Examples

    # Without context (backwards compatible)
    conditional_errors(segment, "AIS", :lenient)

    # With trigger context
    conditional_errors(segment, "AIS", :strict, %{trigger_event: "S03", message_code: "SIU"})

---

*Consult [api-reference.md](api-reference.md) for complete listing*