> ## Documentation Index
> Fetch the complete documentation index at: https://docs.axlprotocol.org/llms.txt
> Use this file to discover all available pages before exploring further.

# Tokenizer Profiles

> Universal parse. Profile-relative compression.

## The Principle

**v2.2 promises universal parse and profile-relative compression, not universal token equivalence.**

The parser works everywhere. Compression efficiency varies by profile.

## Three Tiers

**Universal-safe** (all families): `| : . + $ @ # ! OBS INF CON MRG SEK YLD PRD`

**Likely safe** (profile-dependent): `~ ^ ID: <- => up down EQ`

**Not portable** (legacy only): `π ← → ↑ ↓ µ τ ×`

## Declaring Profile

First packet in any exchange:

```
ID:SYS|OBS.99|@m.PROFILE|@agent.SYS|^v:2.2+^charset:ascii+^tok:neutral+^density:mid|NOW
```

See [Model Entry Points](/overview/model-entry-points) for per-model recommendations.