# Shared types

Look up time bounds, resource links, archive filters, and property types.

## API Reference

Import from `nominal.core`.

Classes

| [`Bounds`](https://dev.nominal.io/python/ref/generated/nominal.core.Bounds.md#nominal.core.Bounds "nominal.core.Bounds") | Start and end timestamps of a time interval, in UTC nanoseconds. |
| --- | --- |
| [`LinkDict`](https://dev.nominal.io/python/ref/generated/nominal.core.LinkDict.md#nominal.core.LinkDict "nominal.core.LinkDict") | A resource link with a URL and an optional display title. |

Enumerations

| [`ArchiveStatusFilter`](https://dev.nominal.io/python/ref/generated/nominal.core.ArchiveStatusFilter.md#nominal.core.ArchiveStatusFilter "nominal.core.ArchiveStatusFilter") | Filter for archive status in search methods. |
| --- | --- |

Type aliases

| [`NominalProperties`](https://dev.nominal.io/python/ref/core/shared-types.md#nominal.core.NominalProperties "nominal.core.NominalProperties") | [`Mapping`](https://docs.python.org/3/library/typing.html#typing.Mapping "(in Python v3.15)")[[`str`](https://docs.python.org/3/builtins/stdtypes.html#str "(in Python v3.15)"), [`str`](https://docs.python.org/3/builtins/stdtypes.html#str "(in Python v3.15)") | [`float`](https://docs.python.org/3/builtins/functions.html#float "(in Python v3.15)")] |
| --- | --- |