# [FORMAT NAME] Evaluation for MARC Data (Rust Implementation)

**Issue:** mrrc-fks.X
**Date:** YYYY-MM-DD
**Author:** [name]
**Status:** Draft | Complete
**Focus:** Rust mrrc core implementation (primary); Python/multi-language support (secondary)

---

## Executive Summary

[2-3 sentences: Is this format viable for MARC data? What are the key findings?]

---

## 1. Schema Design

### 1.1 Schema Definition

```
[Native schema format: .proto, .avsc, .fbs, etc.]
```

### 1.2 Structure Diagram

```
┌──────────────────────────────────────┐
│ MarcRecord                           │
├──────────────────────────────────────┤
│ leader: string (24 chars)            │
│ fields: [Field]                      │
└──────────────────────────────────────┘
         │
         ▼
┌──────────────────────────────────────┐
│ Field                                │
├──────────────────────────────────────┤
│ tag: string (3 chars)                │
│ indicator1: char                     │
│ indicator2: char                     │
│ subfields: [Subfield]                │
└──────────────────────────────────────┘
         │
         ▼
┌──────────────────────────────────────┐
│ Subfield                             │
├──────────────────────────────────────┤
│ code: char                           │
│ value: string                        │
└──────────────────────────────────────┘
```

### 1.3 Example Record

```
[Annotated example of a serialized MARC record in this format]
```

### 1.4 Edge Case Coverage

For each edge case, test it explicitly with the fidelity test set and document results. **All must pass (100%) for recommendation.**

**Data Structure & Ordering (CRITICAL):**
| Edge Case | Test Result | Evidence | Test Record |
|-----------|-------------|----------|-------------|
| **Field ordering** | ☐ Pass / ☐ Fail | **Fields in exact sequence (001, 650, 245, 001 NOT reordered alphabetically/numerically)?** | EC-11 |
| **Subfield code ordering** | ☐ Pass / ☐ Fail | **Subfield codes in exact sequence ($d$c$a NOT reordered to $a$c$d)?** | EC-12 |
| Repeating fields | ☐ Pass / ☐ Fail | Multiple 650 fields in same record preserved in order? | EC-8 |
| Repeating subfields | ☐ Pass / ☐ Fail | Multiple `$a` in single 245 field preserved in order? | fidelity set |
| Empty subfield values | ☐ Pass / ☐ Fail | Does `$a ""` round-trip distinct from no `$a`? | EC-10 |

**Text Content:**
| Edge Case | Test Result | Evidence |
|-----------|-------------|----------|
| UTF-8 multilingual | ☐ Pass / ☐ Fail | Chinese, Arabic, Hebrew text byte-for-byte match? |
| Combining diacritics | ☐ Pass / ☐ Fail | Diacritical marks (à, é, ñ) preserved as UTF-8 (do NOT precompose)? |
| Whitespace preservation | ☐ Pass / ☐ Fail | Leading/trailing spaces in $a preserved exactly (not trimmed/collapsed)? |
| Control characters | ☐ Pass / ☐ Fail | ASCII 0x00-0x1F in data handled gracefully (error or preserved)? |

**MARC Structure:**
| Edge Case | Test Result | Evidence | Test Record |
|-----------|-------------|----------|-------------|
| Control field data | ☐ Pass / ☐ Fail | Control field (001) with 12+ chars preserved exactly, no truncation? | EC-13 |
| Control field repetition | ☐ Pass / ☐ Fail | Duplicate control fields (invalid—test error handling, not preservation) | EC-14 |
| Field type distinction | ☐ Pass / ☐ Fail | Control fields (001-009) vs variable fields (010+) structure preserved? | EC-13, EC-14 |
| Blank vs missing indicators | ☐ Pass / ☐ Fail | Space (U+0020) distinct from null/missing after round-trip? | EC-09 |
| Invalid subfield codes | ☐ Pass / ☐ Fail | Non-alphanumeric codes ("0", space, "$")—test error handling gracefully | EC-15 |

**Size Boundaries:**
| Edge Case | Test Result | Evidence |
|-----------|-------------|----------|
| Maximum field length | ☐ Pass / ☐ Fail | Field at 9998-byte limit handled (preserved exactly or clear error)? |
| Many subfields | ☐ Pass / ☐ Fail | Single field with 255+ subfields preserved with all codes in order? |
| Many fields per record | ☐ Pass / ☐ Fail | Records with 500+ fields round-trip with field order preserved? |

**Scoring:** Count PASS results. If any FAIL, explain in section 2.2. **All edge cases must pass (15/15) for recommendation.**

### 1.5 Correctness Specification

**Key Invariants:**
- **Field ordering:** Must be preserved exactly (no alphabetizing, no sorting, no reordering by tag number)
- **Subfield code ordering:** Must be preserved exactly (e.g., $d$c$a NOT reordered to $a$c$d)
- Leader positions 0-3 and 12-15 may be recalculated (record length, base address); all others **must** match exactly
- Indicator values are **character-based**: space (U+0020) ≠ null/missing
- Subfield values are **exact byte-for-byte** UTF-8 matches, preserving empty strings as distinct from missing values
- Whitespace (leading/trailing spaces) **must** be preserved exactly

---

## 2. Round-Trip Fidelity

### 2.1 Test Results

**Test Set:** fidelity_test_100.mrc
**Records Tested:** 100
**Perfect Round-Trips:** XX/100 (XX%)
**Test Date:** YYYY-MM-DD

### 2.2 Failures (if any)

| Record ID | Field | Criterion | Expected | Actual | Root Cause |
|-----------|-------|-----------|----------|--------|------------|
| | | | | | |

**Failure Investigation Checklist:**
- [ ] **Field ordering changed** (fields reordered alphabetically or by tag number)?
- [ ] **Subfield code order changed** (codes reordered, e.g., $a$c$d instead of $d$c$a)?
- [ ] Encoding issue (UTF-8 normalization, combining diacritics)?
- [ ] Indicator handling (space vs null)?
- [ ] Subfield presence missing (wrong count, missing codes)?
- [ ] Empty string vs null distinction (empty $a "" vs missing $a)?
- [ ] Whitespace trimmed (leading/trailing spaces lost)?
- [ ] Leader position recalculation (only 0-3, 12-15 expected to vary)?
- [ ] Data truncation (field >9999 bytes)?
- [ ] Character encoding boundary issue?

### 2.3 Notes

All comparisons are performed on normalized UTF-8 `MarcRecord` objects produced by mrrc (fields, indicators, subfields, string values), not on raw ISO 2709 bytes.

[Any format-specific observations about data preservation and edge case handling]

---

## 3. Failure Modes Testing

**REQUIRED:** Must complete and pass before performance benchmarking. Formats that panic on invalid input will be rejected.

### 3.1 Error Handling Results

Test the format's robustness against malformed input:

| Scenario | Test Input | Expected | Result | Error Message |
|----------|-----------|----------|--------|---------------|
| **Truncated record** | Incomplete serialized data | Graceful error | ☐ Error / ☐ Panic | _message or "panic"_ |
| **Invalid tag** | Tag="99A" or empty | Validation error | ☐ Error / ☐ Panic | _message or "panic"_ |
| **Oversized field** | >9999 bytes | Error or reject | ☐ Error / ☐ Panic | _message or "panic"_ |
| **Invalid indicator** | Non-ASCII character | Validation error | ☐ Error / ☐ Panic | _message or "panic"_ |
| **Null subfield value** | null pointer in subfield | Consistent handling | ☐ Error / ☐ Panic | _message or "panic"_ |
| **Malformed UTF-8** | Invalid UTF-8 bytes | Clear error | ☐ Error / ☐ Panic | _message or "panic"_ |
| **Missing leader** | Record without 24-char leader | Validation error | ☐ Error / ☐ Panic | _message or "panic"_ |

**Overall Assessment:** 
- ☐ Handles all errors gracefully (PASS)
- ☐ Has 1-2 unguarded panics (needs investigation)
- ☐ Panics on multiple error cases (FAIL)

---

## 4. Performance Benchmarks

### 4.1 Test Environment (Rust Primary)

**Rust benchmarking environment:**
- **CPU:** 
- **RAM:** 
- **Storage:** 
- **OS:** 
- **Rust version:** (and rustc optimization level)
- **Format library version:** (Rust crate)
- **Build command:** `cargo build --release`

**Python secondary (if applicable):**
- **Python version:** 
- **Library version:**
- (Only documented if Python bindings evaluated after Rust primary is complete) 

### 4.2 Results

**Test Set:** 10k_records.mrc (10,000 records)
**Test Date:** YYYY-MM-DD
**Baseline:** See [BASELINE_ISO2709.md](./BASELINE_ISO2709.md)

| Metric | ISO 2709 | [Format] | Delta |
|--------|----------|----------|-------|
| Read (rec/sec) | | | |
| Write (rec/sec) | | | |
| File Size (raw) | | | |
| File Size (gzip) | | | |
| Peak Memory | | | |

### 4.3 Analysis

[Discussion of performance characteristics and comparison to baseline]

---

## 5. Integration Assessment

### 5.1 Dependencies (Rust Focus)

**Rust Cargo dependencies:**

| Crate | Version | Status | Notes |
|-------|---------|--------|-------|
| | | | |

**Total Rust dependencies:** X (direct), Y (transitive)

**Dependency health assessment:**
- [ ] All dependencies actively maintained (commits within 6 months)
- [ ] No known security advisories
- [ ] Compile time impact acceptable (document if >5s incremental build)

### 5.2 Language Support

| Language | Library | Maturity | Priority | Notes |
|----------|---------|----------|----------|-------|
| **Rust** | | ⭐⭐⭐⭐⭐ | **PRIMARY** | Core mrrc implementation |
| Python | | ⭐⭐⭐⭐ | Secondary | PyO3 bindings (if recommended) |
| Java | | ⭐⭐⭐ | Tertiary | Ecosystem context |
| Go | | ⭐⭐ | Tertiary | Ecosystem context |
| C++ | | ⭐⭐⭐ | Tertiary | Ecosystem context |

### 5.3 Schema Evolution

**Score:** X/5

| Capability | Supported |
|------------|-----------|
| Add new optional fields | ☐ Yes / ☐ No |
| Deprecate fields | ☐ Yes / ☐ No |
| Rename fields | ☐ Yes / ☐ No |
| Change field types | ☐ Yes / ☐ No |
| Backward compatibility | ☐ Yes / ☐ No |
| Forward compatibility | ☐ Yes / ☐ No |

### 5.4 Ecosystem Maturity

- [ ] Production use cases documented
- [ ] Active maintenance (commits in last 6 months)
- [ ] Security advisories process
- [ ] Stable API (1.0+ release)
- [ ] Good documentation
- [ ] Community size / adoption

---

## 6. Use Case Fit

| Use Case | Score (1-5) | Notes |
|----------|-------------|-------|
| Simple data exchange | | API integration, file transfer |
| High-performance batch | | Large-scale processing |
| Analytics/big data | | Spark, Hadoop, Parquet ecosystem |
| API integration | | REST/gRPC services |
| Long-term archival | | 10+ year preservation |

---

## 7. Implementation Complexity (Rust)

| Factor | Estimate |
|--------|----------|
| Lines of Rust code | |
| Development time (estimate) | |
| Maintenance burden | Low / Medium / High |
| Compile time impact | |
| Binary size impact | |

### Key Implementation Challenges (Rust)

1. 
2. 
3.

### Python Binding Complexity (Secondary)

- PyO3 binding effort estimate:
- Additional dependencies:
- Maintenance considerations: 

---

## 8. Strengths & Weaknesses

### Strengths

- 
- 
- 

### Weaknesses

- 
- 
- 

---

## 9. Recommendation

### 9.1 Pass/Fail Criteria

**❌ AUTOMATIC REJECTION if:**
- Round-trip fidelity < 100% (any data loss whatsoever)
- Field or subfield ordering changes (reordering by tag/code is data loss)
- Any panic on invalid input (crashes instead of graceful error)
- License incompatible with Apache 2.0
- Requires undisclosed native dependencies

**✅ RECOMMENDATION REQUIRES:**
- 100% perfect round-trip on all 100 fidelity test records
- **Exact preservation of field ordering and subfield code ordering**
- All edge cases pass (15/15 synthetic tests)
- Graceful error handling on all 7 failure modes
- 0 panics on any invalid input
- Clear error messages for all error cases

### 9.2 Verdict

**Select one:**
- ☐ **RECOMMENDED** — Format meets all pass criteria; suitable for production use in mrrc
- ☐ **CONDITIONAL** — Format meets fidelity/robustness but has integration concerns (list them)
- ☐ **NOT RECOMMENDED** — Format fails one or more pass criteria

### 9.3 Rationale

[2-3 paragraphs explaining the verdict. Include:]
- **Fidelity:** Summary of round-trip testing (100%, or list any failures)
- **Robustness:** Summary of error handling (all passed, or which scenarios failed)
- **Performance:** How it compares to ISO 2709 baseline (if fidelity/robustness pass)
- **Ecosystem:** Key integration factors (dependencies, build complexity)
- **Use cases:** Where this format excels or falls short

---

## Appendix

### A. Test Commands

```bash
# Build
# Run benchmarks
# Validate round-trip
```

### B. Sample Code

```rust
// Key implementation snippets
```

### C. References

- [Format specification]()
- [Rust library documentation]()
- [Related MARC format discussions]()
