In plain terms: A source is something that comes in (a drawing sheet, a
survey report, a Class rule). A decision is something the system reasons out
from those sources. Forge keeps them in separate places on purpose.
Sources: what comes in
A is any input: drawing sheets, survey and inspection reports, thickness measurement records, Class rules, CAD files, repair histories, datasheets. Two things are always true of a source:- It is immutable once ingested. Once a source is in the system, it is locked. It is never quietly edited to make a later result work out.
- It carries its version, authority, provenance, and moment in time. The system always knows which edition of a rule this is, which survey this came from, how much weight it carries, and exactly where it came from.
Decisions: what gets reasoned out
A decision is what the system concludes from sources: that a reconstructed component is supported by the drawings, that a rule applies, that two records conflict, that a repair changed the structure, what it replaced. Decisions are first-class objects. They live in the with their own structure, their own life cycle, and their own . And critically, a decision is replayable: given the same sources at the same versions, the same decision should be reconstructable from scratch.Three trust levels for sources
Not every source carries the same weight. Every source in the registry is tagged with one of three trust levels:
Note where drawings land. A drawing is evidence about the ship, not authority
over it. It records what someone measured or intended at one moment. When a
drawing and a recent survey disagree, that is a conflict between two pieces of
evidence to be resolved, not a rule being broken.
This trust grade is also separate from the document type. The same Class rules
can be authority for one vessel and reference for another under a different
society or flag. A sister ship’s records are evidence when reasoning about that
hull and reference when reasoning about this one.
The rule that ties it together
Every claim the system makes must cite its source. A claim that a rule applies cites that rule and its version. A claim about a dimension cites the measurement record. A claim that a component is supported by the drawings cites the sheets and regions that support it.Nothing the system says is ungrounded.That is what makes a decision defensible later: you can always trace it back to the exact sources, at the exact versions, that produced it.