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+# Verification Note: pdftract-1l6wn - BMC/BDC/EMC Operator Parsers
+
+## Bead Description
+
+Implement the 3 marked-content operators: `BMC /Tag`, `BDC /Tag <<props>>` or `BDC /Tag /PropName`, and `EMC`. Maintain a `marked_content_stack: Vec<MarkedContentFrame>` on the page executor.
+
+## Status: ALREADY IMPLEMENTED ✅
+
+The BMC/BDC/EMC operator parsers and `MarkedContentStack` are already fully implemented in the codebase.
+
+## Implementation Location
+
+### 1. MarkedContentStack
+- **File**: `crates/pdftract-core/src/parser/marked_content_stack.rs`
+- **Structure**: `MarkedContentStack` with `Vec<MarkedContentFrame>`
+- **Depth limit**: 64 (enforced with `MAX_MC_DEPTH` constant)
+- **Diagnostics**: `EmcWithoutBmc`, `MarkedContentDepthExceeded`
+
+### 2. MarkedContent Operators
+- **File**: `crates/pdftract-core/src/parser/marked_content_operators.rs`
+- **Functions**:
+  - `parse_bmc(stack, tag)` - BMC operator
+  - `parse_bdc(stack, tag, props, resources, default_off_ocgs, diagnostics)` - BDC operator
+  - `parse_emc(stack)` - EMC operator
+
+### 3. Integration into Content Stream
+- **File**: `crates/pdftract-core/src/content_stream.rs`
+- **Function**: `execute_with_do` (lines 875-965)
+- The marked-content stack is instantiated and BMC/BDC/EMC operators are wired into the main content stream execution loop.
+
+## Acceptance Criteria Verification
+
+All acceptance criteria are covered by passing tests:
+
+| Criterion | Test Name | Status |
+|-----------|-----------|--------|
+| BMC /Span EMC: stack push then pop, balanced | `test_push_bmc` + `test_pop_emc` | ✅ PASS |
+| BDC /Span <</MCID 42>> EMC: frame with mcid=Some(42) | `test_parse_bdc_with_inline_dict_mcid` | ✅ PASS |
+| BDC /P /MyProps EMC with resolved /MCID 7 | `test_parse_bdc_with_property_name_found` | ✅ PASS |
+| BDC /P /UnknownProps EMC: diagnostic for unknown prop name | `test_parse_bdc_with_property_name_not_found` | ✅ PASS |
+| EMC without BMC: EMC_WITHOUT_BMC diagnostic, no panic | `test_pop_emc_underflow` | ✅ PASS |
+| 64 nested BMC: succeeds; 65th emits depth diagnostic | `test_stack_depth_limit` | ✅ PASS |
+
+## Test Results
+
+```
+cargo test -p pdftract-core --lib 2>&1 | grep -E "test.*marked_content|test.*parse_bmc|test.*parse_bdc|test.*parse_emc"
+```
+
+All 57 marked-content related tests passed:
+- 18 tests in `parser::marked_content_stack::tests`
+- 30 tests in `parser::marked_content_operators::tests`
+- 9 tests in other modules using marked-content features
+
+## Key Implementation Details
+
+### INV: Marked Content Stack Independence
+The marked-content stack is independent of the graphics state stack. The q/Q operators do NOT affect it (per PDF spec section 14.5). This is correctly implemented in `content_stream.rs` where the two stacks are managed separately.
+
+### Property Name Resolution
+`ResourceDict::lookup_properties()` is used to resolve property names in BDC operators. The implementation handles both inline dictionaries and property resource names.
+
+### MCID Extraction
+- Supports Integer and Real (whole number) MCID values
+- Negative MCID values are rejected per spec ("non-negative integer")
+- Missing /MCID results in `mcid=None` (valid for BMC or BDC without properties)
+
+### OCG Hidden Flag (bead pdftract-1q19p)
+The `is_hidden` flag on `MarkedContentFrame` tracks content within default-OFF Optional Content Groups. This is integrated into the BDC parser for /OC tags.
+
+## Conclusion
+
+No implementation work was required for this bead. The BMC/BDC/EMC operator parsers and `MarkedContentStack` were already fully implemented with comprehensive test coverage. All acceptance criteria are met.