RFC: Add Missing Prepositions 'by' and 'at' to Core Specification

[KrisSimon]

Problem

ARO-0001 defines 8 prepositions but the codebase uses at least 2 more that aren't formally specified.

Currently Defined (ARO-0001)

• from (source/origin)
• for (purpose/target)
• with (accompaniment/using)
• to (destination)
• into (insertion)
• on (location/event)
• via (method/path)
• as (alias/role)

Undocumented Prepositions

Preposition	Introduced In	Usage
by	ARO-0037	Split delimiter, Sort criterion
at	PR #50	Filesystem location

Examples

(* 'by' - delimiter/criterion *)
<Split> the <parts> from the <string> by /,/.
<Sort> the <sorted> from the <list> by <field>.

(* 'at' - filesystem location - from PR #50 *)
<Make> the <directory> at the <path: "./output">.

Issue

1. These prepositions are used in working code
2. Neither is defined in ARO-0001
3. Semantics are not formally specified
4. PR feat: add Make verb for natural directory creation syntax #50 adds at without updating ARO-0001

Proposed Solution

Add both to ARO-0001:

Preposition	Semantic	Example
by	Delimiter/criterion	<Split> ... by /pattern/.
at	Location/path	<Make> ... at <path>.

Semantic Definitions

by = Using as the basis for division or ordering

• For Split: the pattern that separates elements
• For Sort: the field used for comparison

at = At a specific location/path

• For Make: the filesystem path to create at
• Natural English: "make directory at path"

Related: PR #50

PR #50 (feat: add Make verb for natural directory creation syntax) adds:

• at preposition to the parser
• <Make> as verb for directory creation
• Example: <Make> the <directory> at the <path: "./output">

This PR should be reviewed alongside ARO-0001 updates.

Questions

1. Should at and by be full prepositions or context-specific keywords?
2. Are there other undocumented prepositions in use?
3. Should ARO-0001 be updated before PR feat: add Make verb for natural directory creation syntax #50 merges?

[KrisSimon]

Accepted as an issue.