Proposal: Existing Field Values and JSON Validation

Status

Accepted for OAA 1.0

Summary

Tighten the meaning and validation of existing base fields without adding new metadata fields.

Motivation

Shape-only validation permits impossible sizes and dates, empty required identifiers, and parser-dependent JSON. These ambiguities affect reliable interchange even without expanding the field model.

Specification Changes

• When present and non-null, size_bytes MUST be an integer greater than or equal to zero and MUST equal the embedded file’s uncompressed byte length.
• When present and non-null, pixel width and height MUST be positive integers, and each of dpi_x and dpi_y MUST be a finite positive number. These are the existing horizontal and vertical DPI fields; this decision adds no combined DPI field.
• Pixel and DPI constraints validate the supplied metadata. OAA conformance MUST NOT require decoding or rendering embedded media or installing image codecs to verify those values against media contents.
• When present and non-null, base date-only fields MUST contain real calendar dates in YYYY-MM-DD form, not merely strings matching that shape.
• Required names, titles, and identifiers MUST NOT be empty or whitespace-only.
• Writers SHOULD omit optional fields whose values are unavailable. null MUST be used only where the field definition explicitly permits it; allowed nulls remain valid and are exempt from the numeric and date-value constraints above.
• An external link url MUST be either the existing empty-string sentinel or a valid absolute URL that is not a local-file reference. Readers MUST NOT automatically fetch or execute a URL merely because it appears in a manifest.
• Price and estimate fields remain display strings. Structured amounts and currencies are deferred; this decision introduces no new fields or value sets.
• Manifests MUST be valid JSON. Readers MUST reject duplicate object member names and non-JSON numeric tokens such as NaN or Infinity.
• Base-field value rules MUST NOT be imposed on unrelated, same-named keys inside provider extensions.

Compatibility Impact

Some values accepted by permissive 0.1 readers or schemas will not meet 1.0 requirements. These checks belong in the explicit 1.0 contract, with schema checks supplemented by archive-aware validation where needed.

Examples

2024-02-29 is a valid date; 2025-02-29 is not. An empty embedded file can have size_bytes of zero, but an image dimension of zero is invalid. dpi_x: null represents an unknown value where null is allowed; dpi_y: 300 is a valid positive DPI value. A price such as “Price on request” remains display text.

Open Questions

No open design question blocks integration. Structured monetary metadata requires a separate future proposal and community evidence.