# Core System **Namespace:** `mp_units` **Module:** `mp_units.core` **Header:** `` ## Dimensions | Name | Symbol | |------|:------:| | `dimension_one` | 1 | ## Quantities | Quantity | Character | Dimension | is_kind | Kind of | Parent | Equation | Hierarchy | |----------|:---------:|:---------:|:-------:|:-------:|:------:|----------|:---------:| | dimensionless | Real | 1 | ✓ | [dimensionless](core.md#dimensionless) | — | — | [view](../hierarchies/dimensionless.md) | ## Units | Unit Name | Symbol | unit_symbol | Definition | |-----------|:------:|:-----------:|------------| | one | 1 | — | — | | parts_per_million | ppm | — | mag_ratio<1, 1'000'000> * [one](core.md#one) | | per_mille | ‰ (%o) | — | mag_ratio<1, 1000> * [one](core.md#one) | | percent | % | — | mag_ratio<1, 100> * [one](core.md#one) | | pi | π (pi) | — | mag * [one](core.md#one) | | ppm | — | — | alias to [mp_units::parts_per_million](core.md#parts_per_million) | | π | — | — | alias to [mp_units::pi](core.md#pi) |