Rule Tables and Grade Rules Inside DXF AAMA Files

A grade rule is a set of delta values: how far a graded point moves in the x and y directions for each size increment relative to the base size. A point on the shoulder tip might move 0.6 cm in x and 0.2 cm in y per size, while a point on the center front stays fixed. Each cardinal point on a piece references one rule by number.

Because the rule stores a movement, not an absolute coordinate, the same rule can be reused across many points and pieces. This is efficient and is why a well-built rule table is compact even for a wide size range. The base geometry is drawn once; the grade is layered on top as arithmetic.

The AAMA specification reserves specific layers and entity conventions for grade data. Rule tables typically live in dedicated blocks separate from the piece outlines, and each graded point on a piece is tagged with the rule number it obeys. Size line increments are recorded so the importing system knows how many sizes exist and what the step is.

When a receiving CAD package supports AAMA fully, it reads the rule numbers, applies the deltas and reconstructs the nested sizes. When it supports only the geometric subset, it draws the base outline and silently discards the rules, which is the classic reason a graded file arrives as a single size.

• Base size: the drafted master from which all deltas are measured, often the middle of the range.
• Delta x and delta y: the per-step movement of each cardinal point, positive or negative.
• Size line: the ordered list of sizes, defining how many steps sit above and below the base.
• Rule number: the identifier linking a point to its movement values in the table.
• Break points: sizes where the increment changes, common between petite, regular and plus ranges.

Two systems can both claim DXF support yet disagree on grade because AAMA is a superset of plain DXF. Generic DXF describes lines, arcs and text; it has no concept of a grade rule. The apparel extensions add that meaning through agreed layer names and block structures, so both ends must implement the same extensions.

Before shipping a graded pattern, confirm that the receiving software reads AAMA rule tables and not just the underlying geometry. A quick test is to export one graded piece, import it, and count the nested sizes. If only the base appears, the rules were dropped in transit.

1. 1.Open the graded nest and confirm the size line lists every intended size in order.
2. 2.Verify that fixed points, such as center front, carry a zero-movement rule rather than no rule.
3. 3.Spot-check a girth measurement across three sizes to confirm increments are even.
4. 4.Re-import your own export into a clean file and count the sizes that reconstruct.
5. 5.Record the base size and unit in the delivery notes so the recipient configures import correctly.

Made-to-measure work often sidesteps rule tables entirely. Instead of shipping a graded nest, the pattern is generated at one exact set of measurements and delivered as a single net size, which removes any risk of grade being lost in translation. The file is smaller and simpler, and there is nothing for the recipient to misinterpret.

Minerva Patterns supplies made-to-measure digital patterns in DXF AAMA, PLT and PDF, generated to a customer's own measurements, so most orders arrive as a clean single-size file rather than a graded nest that depends on the recipient's software reading rule tables correctly.