Module errors 

Typed error enums for identifier validation and conversion.

All failure paths return a typed Result — no panic!(), no unwrap(), no string errors. Each variant carries enough context for the caller to report precisely what was wrong and where.

Two enums separate the two failure domains:

• ValidationError — a string is not a well-formed identifier: wrong length, wrong charset, a failed check digit, or a structural rule.
• ConversionError — a structurally valid identifier cannot be mapped to the requested target identifier.

Both implement core::fmt::Display and core::error::Error, so they compose with ? and with dyn Error even under #![no_std].

References

• ISO 6166 (ISIN), ISO 7064 (check characters), ISO 9362 (BIC), ISO 10383 (MIC), ISO 10962 (CFI), ISO 17442 (LEI) — the governing standards whose rules these errors report.

Enums

ConversionError

Error returned when one identifier cannot be converted into another.

ValidationError

Error returned when a string is not a well-formed securities identifier.