---
numbering:
  title: true
---

# `arch.base`: Architectonic Base Primitives

```{py:currentmodule} arch.base
```

The `base` subpackage defines the three primitives every other module builds on: `Lang`, an enum of the source languages the architectonic recognizes; `Idx`, the four-level hierarchical index that addresses a cell within the tree; and `Cell`, the SQLModel row pairing an index with its names, division, and moments.
`IdxType` is the SQLAlchemy column type that round-trips `Idx` values through the database.

```{toctree}
:maxdepth: 2
base.Lang
base.Idx
base.IdxType
base.Cell
```