VectorPaint invented two-flag cards: audit sixteen combinations through rows and columns

English translation of the Chinese original, translated on 2026-11-05. Original publication dates, attribution, code and version notes are retained.

Two flags with four invented directions each produce sixteen states, but their positions and directions must stay consistent throughout the card. Build a static coding exercise whose personal rules are unsuitable for real communication or emergency signalling. VectorPaint supplies shapes and layout, not automatic encoding, decoding or an interactive semaphore component.

Define left/right slots and four directions

Create a 1200 by 1000 pixel canvas. Define left/right by image position, never switching to a person’s own sides. Each slot has states 0 up, 1 right, 2 down and 3 left, explained through arrows or pole direction. Prototype one cell with each flag in its own half so crossings cannot confuse origin. State the invented rule beside it without assigning real alphabet meanings. A two-digit ID places left state first and right second: 01 means left-up/right-right. Fix that order before laying out the table.

Preserve and verify four directional source symbols

Build a recognisable pole-and-flag symbol, then copy/rotate it into four directions around consistent references. Inspect the whole symbol so a fabric corner is not mistaken for the pole’s direction. Place 0–3 below, preserving readable text rather than rotating it with the shape. Hide numbers to read directions, then restore and check them. Two colours may distinguish slots, but position or labels must also identify them for monochrome or colour-vision differences. Name all four sources so every copy remains traceable.

Build four rows and columns with fixed meanings

Rows represent left states 0–3 and columns right states 0–3, with both direction and number in headers. Each cell contains a pair, producing 4×4=16 states. Use equal widths and separate flag spaces; headers are not a fifth data row. Inspect empty cells and headers first, reading row/column meanings and checking that the right state has not been assigned to rows. Hand-drawn references remain artwork you may keep or hide; check native-grid output separately. This is manually laid out, not a built-in coding matrix.

Place left flags by row and right flags by column

Complete row one with the left flag always up and right flags up/right/down/left, IDs 00–03. Row two keeps the left flag rightward with the same column order, then continue the remaining rows. Arbitrary per-cell rotation would break the matrix. Read left direction, right direction and both ID digits at each placement. Group symbols and IDs appropriately, checking selection when changing copied cells so neither flag is missed. Before decoration, verify all sixteen cells against headers; IDs cannot disguise repeated wrong directions.

Use uniqueness checks to find duplicates and omissions

List all sixteen pairs 00–33 externally and check them against the table. Unique IDs do not establish unique graphics, so hide IDs and decode both directions manually. Duplicate symbols often mean a flag was not changed after copying; changing its number would only hide the error. Require every pair once, not merely sixteen cells. A deliberately missing exercise cell needs explicit labelling and a separately saved answer, rather than retaining a complete-set claim. This is a human audit, not automatic uniqueness checking in a static image.

Update all affected cells when changing a convention

In a copy, redefine state 1 as left and state 3 as right. Update legend and sources first, then inspect both affected rows and columns, including intersections. IDs remain the same but meanings change, so old decoding no longer applies. Updating headers alone leaves old instances; do not also swap slot order in this test. Restore the original convention or name a second rule version. This reveals definition-to-instance dependencies: ordinary copies do not understand changed rules, so one edit can require many checks.

Retain the full legend and reading order in output

Save directional sources, matrix and audit list. Inspect smallest IDs and slot spacing after export, including monochrome slot recognition. Keep legend, headers and invented-use scope rather than cropping out sixteen unexplained icons. Name personal two-flag code, rule revision and dimensions and reopen it to exclude test conventions. A separately shared cell still needs the left-first/right-second explanation. This is neither an interactive game nor a professional signalling manual; actual communication requires its applicable formal standard, not extensions of these exercise rules.

Troubleshoot slot order before changing symbols

If 01 is read as left-rightward/right-upward, reversing the two fields, check ID order and image-versus-person left/right. A wrong entire column points to its source rather than sixteen independent rotations; one wrong cell points to copy selection. If cells are skipped despite clear headers, improve spacing and IDs instead of deleting legends for density. For inverted text, inspect shape/text rotation scope. Repeat row-wise, column-wise and ID-hidden checks. Each cell should map uniquely to its pair rather than merely completing sixteen similar images.