# Deterministic Oracles Spectra offers semi-deterministic pricing models for the Principal Token (PT). Those oracles match the redemption value of the PT at maturity, that is one unit of underlying adjusted by the `ptRate` . We implement various discounting models, whose logic we explain in the subsequent pages. To fetch the latest PT price in terms of underlying, one queries the `latestRoundData()` method from the `SpectraPriceOracle` contract. Dependent on the discounting model chosen at construction, this will either return the PT price in underlying discounted according to the linear discount model or according to the zero-coupon bond model. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://dev.spectra.finance/integration-reference/spectra-oracles/deterministic-oracles.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.