---
title: SAIF.Framework.BaseN business rules
summary: Enumerated business rules with per-rule trigger, enforcement, and outcomes.
status: draft
owner: <owner>
last_reviewed: 2026-07-23
library: SAIF.Framework.BaseN
reference_type: package
---

# SAIF.Framework.BaseN business rules

This page captures business rules enforced by this library.

## BR-001: Hexadecimal digit must not exceed base 16

| Field | Value |
| --- | --- |
| **Statement** | A digit value processed by `HexConverter` must not exceed the converter's base (16). |
| **Trigger** | `HexConverter.ConvertAlphaToNumeric` or `HexConverter.ConvertNumericToAlpha` receives a value greater than `Base` (16). |
| **Enforcement** | `HexConverter.vb` — throws a `ConverterException`. |
| **Outcome** | The invalid digit is rejected; the caller receives a `ConverterException` with message `"'{value}' must be less than '{base}'"`. |
| **Source** | `SAIF.Framework.BaseN\HexConverter.vb`, `SAIF.Framework.BaseN\ConverterException.vb` |

---

## BR-002: Excel (base-26) digit must not exceed base 26

| Field | Value |
| --- | --- |
| **Statement** | A digit value processed by `ExcelConverter` must not exceed the converter's base (26). |
| **Trigger** | `ExcelConverter.ConvertNumericToAlpha` or `ExcelConverter.ConvertAlphaToNumeric` receives a value greater than `Base` (26). |
| **Enforcement** | `ExcelConverter.vb` — throws a `ConverterException`. |
| **Outcome** | The invalid digit is rejected; the caller receives a `ConverterException`. |
| **Source** | `SAIF.Framework.BaseN\ExcelConverter.vb`, `SAIF.Framework.BaseN\ConverterException.vb` |

---

## BR-003: Excel-style base-26 conversion is bijective (no zero digit)

| Field | Value |
| --- | --- |
| **Statement** | Excel-style base-26 formatting has no zero digit; a "Z" position rolls over into an additional digit, mirroring spreadsheet column naming (A, B, … Z, AA, AB, …). |
| **Trigger** | Any digit in the array equals `0` during `ExcelConverter.FormatBaseN`. |
| **Enforcement** | `ExcelConverter.vb` — the `FormatBaseN` override adjusts a zero digit to the base value (26) and decrements/rolls the preceding digit(s) accordingly. |
| **Outcome** | Produces correct Excel-style column-letter output instead of a literal "0" digit. |
| **Source** | `SAIF.Framework.BaseN\ExcelConverter.vb` |

---

## BR-004: Non-numeric input to the default alpha-to-numeric conversion is treated as zero

| Field | Value |
| --- | --- |
| **Statement** | Non-numeric input to the default alpha-to-numeric conversion is treated as zero rather than raising an error.* |
| **Trigger** | `ConverterBase.ConvertAlphaToNumeric` receives a non-numeric string and no subclass override applies (used by `BinaryConverter` and `OctalConverter`, which do not override alpha/numeric conversion). |
| **Enforcement** | `ConverterBase.vb` — returns `0` silently when `IsNumeric(input)` is `False`. |
| **Outcome** | Callers receive `0` for invalid input instead of an exception; only `BinaryConverter` and `OctalConverter` are affected by this default, non-strict behavior. |
| **Source** | `SAIF.Framework.BaseN\ConverterBase.vb`, `SAIF.Framework.BaseN\BinaryConverter.vb`, `SAIF.Framework.BaseN\OctalConverter.vb` |

## Notes
- `HexConverter` and `ExcelConverter` enforce strict bounds checking ([BR-001](business-rules.md#br-001-hexadecimal-digit-must-not-exceed-base-16), [BR-002](business-rules.md#br-002-excel-base-26-digit-must-not-exceed-base-26)), while `BinaryConverter` and `OctalConverter` rely on the non-strict default described in [BR-004](business-rules.md#br-004-non-numeric-input-to-the-default-alpha-to-numeric-conversion-is-treated-as-zero).
- No inherited business rules were found; this library has no base classes or services from dependency framework libraries.

## Related documentation
- [Index](index.md)
- [Overview](overview.md)
- [Architecture](architecture.md)
- [Dependencies](dependencies.md)
- [Operations and processes](operations-processes.md)
- [Configuration](configuration.md)
- [API reference](api/index.md)

> **Note:** Statements marked with `*` were inferred from code structure, naming conventions, or
> contextual evidence where direct confirmation was not available in source artifacts. Statements
> marked with `**` could not be confirmed; treat as unknown until verified.

## Sources
- `SAIF.Framework.BaseN\HexConverter.vb`
- `SAIF.Framework.BaseN\ExcelConverter.vb`
- `SAIF.Framework.BaseN\ConverterBase.vb`
- `SAIF.Framework.BaseN\BinaryConverter.vb`
- `SAIF.Framework.BaseN\OctalConverter.vb`
- `SAIF.Framework.BaseN\ConverterException.vb`