# Operators

Learn how PLLM describes model operations independently of model family and runtime.

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Document ID: `pllm.docs.operators`  
Release: `0.1.0`

Operators describe what a model does without depending on model-family names or a
specific runtime. Plans represent projections, normalization, rotary embeddings,
attention, recurrent and convolutional state, nonlinear activation, residuals,
selection, and input or output boundaries with explicit shapes and settings.

A compiler profile lists the operators it can execute. Unknown or unsupported
operations appear in `PlanCoverage` and stop compilation. PLLM never silently
replaces them with plaintext or approximate work. Research methods also use these
shared operators instead of relying on model-specific weight names.

An operator in a model plan shows only that PLLM can describe it. Read
[numeric semantics and model quality](/learn/numeric-semantics-and-model-quality/)
for why operator coverage alone is insufficient. See
[compiler](/sdk/pipeline/compiler/) for execution support and
[numerics](/sdk/build/numerics/) for integer and approximation requirements.

The bounded [SiLU activation](/sdk/build/operators/activation-silu/) is the first
operator with an experimental plan-bound protected executor. Other listed
operators remain semantic records until their compiler and runtime coverage is
implemented.

## Python SDK example

```python
from pathlib import Path

from pllm import lower_model

fixture = Path("crates/pllm-models/tests/fixtures/mini-coder-4b-c87892d-config.json")
plan = lower_model(fixture.read_bytes(), batch=1, max_input_tokens=16, max_new_tokens=4)
operators = {operation["operator"] for operation in plan.prefill["operations"]}
assert {"linear", "rotary_embedding", "silu", "softmax"} <= operators
assert plan.coverage().complete is False
```

API: [Python SDK objects and signatures](/sdk/reference/python/pllm/#objects-and-signatures)

Run this example from a PLLM source checkout; package installations do not include
the checked-in fixture. This inspects semantic operators; it does not establish
execution coverage.