Which axis should a 1‑D array align to when broadcasting against a 2‑D array in APL?

Goal

Determine the axis alignment of a 1‑D operand when combined with a 2‑D operand under APL broadcasting semantics.

Constraints

The language specification promotes the right‑hand operand’s shape to the left‑hand operand’s shape, but does not specify the axis for a 1‑D/2‑D combination. Dialects diverge: Dyalog aligns on the last axis, treating the vector as a row; GNU APL aligns on the first axis, treating it as a column.

Unresolved Questions

1. Which axis should be considered the default for broadcasting a 1‑D array against a 2‑D array?
2. Should the APL standard mandate a single axis, or allow dialects to choose?
3. Do any dialects expose a configuration option to select the alignment?