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0648ae lisa 2026-06-08 09:18:19
Add C05 student wiki pages: design tools, annotation, traceability Six DRAFT pages under /sd/C05 targeting common rubric-boundary errors: - Sketch vs Mock-up (C5-1) — embeds two videos - Data Dictionary — Format is not Type (C5-1) - IPO Charts — Process Means Steps (C5-1) - VCAA Pseudocode — Not Python (C5-1) - The Annotation Verb Ladder (C5-2) - Connect the Dots — design traceability (C5-3) Pages 2-6 have video slots pending teacher selection. Home index reorganised by indicator. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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> **DRAFT** — under teacher review.
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# Data Dictionary — "Format" Is Not "Type"
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The Hamilton and Alexandra College · Year 12 · 2026
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The single most common data-dictionary error is writing a data **type** in the **Format** column. They are not the same thing. This page explains the difference, shows you what correct entries look like, and maps to the VCAA band descriptors.
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---
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## The core distinction
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**Type** is the *kind* of data — what category it belongs to.
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**Format** is the *storage or display pattern* — the exact shape the value takes.
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These are different answers to different questions:
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| Question | Column | Example answer |
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|---|---|---|
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| What kind of data is this? | **Type** | `Integer` |
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| What does a valid value look like? | **Format** | `999999` (fixed 6 digits) |
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If you write `Integer` in the Format column, you have answered the wrong question. A marker sees that and knows you have conflated two concepts.
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---
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## Format notation key
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The format strings use a small set of symbols — memorise these:
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| Symbol | Meaning |
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|---|---|
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| `9` or `N` | One digit (0–9) |
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| `X` | One uppercase letter |
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| `x` | One lowercase letter |
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| `YYYY` | Four-digit year |
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| `MM` | Two-digit month |
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| `DD` | Two-digit day |
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| Separator (`,` `.` `-`) | Literal separator character |
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So `999999` means "exactly six digits". `Xxxxxxxxxxxxxxx` means "one uppercase letter followed by lowercase letters — the number of `x` characters shows the maximum length".
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---
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## Worked example — a complete data dictionary
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These rows come from a client-management system. Read across each row and notice that Type and Format sit in separate columns and say different things.
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| Field | Type | Size | Format | Example |
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|---|---|---|---|---|
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| `id` | Integer | 6 | `999999` | 201940 |
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| `firstName` | Text | 50 | `Xxxxxxxxxxxxxxx` | Jane |
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| `lastName` | Text | 50 | `Xxxxxxxxxxxxxxx` | Smith |
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| `DOB` | Date/time | 8 | `YYYY-MM-DD` | 2001-07-19 |
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| `clubMember` | Boolean | 1 | `true/false` | true |
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| `memberYears` | Integer | 2 | `NN` | 6 |
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| `sales` | FloatingPoint | 8 | `NN,NNN.NN` | 12,543.76 |
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Notice what each Format entry tells you that the Type alone does not:
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- `id` is an Integer — but the Format `999999` tells you it is always **6 digits**, not 1 or 2.
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- `firstName` is Text — but `Xxxxxxxxxxxxxxx` tells you it starts with a **capital** and the rest are lowercase.
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- `DOB` is Date/time — but `YYYY-MM-DD` fixes it to **ISO format**, not DD/MM/YYYY or MM-DD-YYYY.
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- `sales` is FloatingPoint — but `NN,NNN.NN` specifies a **thousands separator** and exactly **2 decimal places**.
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---
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## Why Format matters
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Format entries do three jobs in your design documentation:
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- **Data consistency** — every value entered follows the same shape, so comparisons and sorting work correctly.
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- **Validation** — your software can reject an entry that does not match the pattern (e.g., a date typed as `19-07-01` instead of `2001-07-19`).
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- **Readability** — another developer reading your data dictionary can reproduce the exact storage structure without guessing.
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A Format column filled with type names (`Integer`, `String`, `Boolean`) gives you none of these benefits — it duplicates the Type column and adds no information.
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---
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## VCAA band levels — what's required at each step
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VCAA defines a data dictionary as specifying variables, arrays, and GUI objects with reference to data types, data structures, and data sources. The level descriptors build upward:
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| Level | What you must include |
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| **Level 3** | Reference to **data types** (Integer, Text, Boolean, Date/time, FloatingPoint) |
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| **Level 5** | Data types **and data structures** (arrays, records — not just scalar variables) |
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| **Level 7** | Data types, data structures **and data sources** (where does each value come from — user input, database, calculation?) |
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You cannot skip levels. If your dictionary has no data structures, you cannot claim Level 5 or above.
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---
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## Common mistakes
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### Mistake 1: Format = Type
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> ~~`Format: Integer`~~
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Write the pattern instead: `999999`, `NN`, etc. If you cannot write a pattern, leave a note and revisit — but do not copy the Type column.
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### Mistake 2: Missing data sources at Level 7
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> ~~(no Source column, or Source column left blank for half the rows)~~
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Every field at Level 7 needs a source. "User input", "calculated from `sales` total", "retrieved from customer database" — these are all valid. Blank is not.
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### Mistake 3: Vague sizes
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> ~~`Size: large`~~
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Size must be a number — the number of characters, bytes, or digits the field can hold. If you do not know, look at your data (the longest plausible value) and choose a round number that covers it.
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### Mistake 4: Only scalar variables
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A dictionary that lists only individual variables but no arrays or records cannot score Level 5 or above. If your design uses a list of items or a record structure, include it.
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---
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## 🎬 Watch
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> [!NOTE]
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> Video coming soon.
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**🎯 Watch for:** how an experienced developer reads a Format string and immediately knows the exact shape of valid data — something the Type alone can never tell you.
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---
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## Check Your Understanding
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1. A student writes `Text` in the Format column for a `lastName` field. What is the mistake, and what should they write instead?
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>| ### Answer
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>| `Text` is a **type**, not a format. It duplicates the Type column and adds nothing. The correct Format entry is `Xxxxxxxxxxxxxxx` — one uppercase letter followed by lowercase letters, with the number of `x` characters indicating maximum length (e.g. 15 for a 15-character maximum).
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2. Your data dictionary has variables and arrays but no data sources. Which VCAA level can you reach, and which is out of reach?
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>| ### Answer
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>| You can reach **Level 5** (data types and data structures). **Level 7** is out of reach because it requires data sources as well. Add a Source column and fill it in for every row to unlock Level 7.
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3. What does the Format string `NN,NNN.NN` tell you that the Type `FloatingPoint` does not?
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>| ### Answer
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>| It tells you the value uses a **thousands separator** (`,`) and is stored to exactly **two decimal places**. `FloatingPoint` alone does not specify either of these — you could have `12543.7` or `12,543.759` and both would be valid floats, but only `12,543.76` matches the format.
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---
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## See also
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- [IPO Charts — Process Means Steps](/sd/C05/IPO%20Charts%20-%20Process%20Means%20Steps)
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- [Sketch vs Mock-up](/sd/C05/Sketch%20vs%20Mock-up)
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- [Ryan's Tutorials — Data Dictionary](https://ryanstutorials.net/software-design-and-development/data-dictionary.php) — AU secondary-pitched; shows a "Format for Display" column with N/X notation
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- [C05 Resources](/sd/Resources/C05-Resources)
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