flixOpt
diff --git a/‎.github/workflows/tests.yaml‎
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diff --git a/‎CHANGELOG.md‎
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diff --git a/‎docs/user-guide/core-concepts.md‎
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diff --git a/‎docs/user-guide/mathematical-notation/dimensions.md‎
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diff --git a/‎docs/user-guide/mathematical-notation/elements/Flow.md‎
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@@ -6,7 +6,7 @@ on:
   pull_request:
     branches: ["**"]
   workflow_dispatch:
-  workflow_call:  # Allow release.yaml to call this workflow
+  workflow_call:  # Allow release.yaml to call this workflow.
 
 concurrency:
   group: ${{ github.workflow }}-${{ github.ref }}
 
@@ -51,14 +51,76 @@ If upgrading from v2.x, see the [v3.0.0 release notes](https://github.com/flixOp
 
 ## [Unreleased] - ????-??-??
 
-**Summary**:
-
-If upgrading from v2.x, see the [v3.0.0 release notes](https://github.com/flixOpt/flixOpt/releases/tag/v3.0.0) and [Migration Guide](https://flixopt.github.io/flixopt/latest/user-guide/migration-guide-v3/).
+**Summary**: Renamed OnOff terminology to Status terminology for better alignment with PyPSA and unit commitment standards.
 
 ### ✨ Added
 
 ### 💥 Breaking Changes
 
+**Renamed `OnOffParameters` → `StatusParameters`**: Complete terminology update to align with industry standards (PyPSA, unit commitment). This is a clean breaking change with no backwards compatibility wrapper.
+
+**Class and Constructor Parameters:**
+
+| Category | Old Name (OnOffParameters) | New Name (StatusParameters) | Notes |
+|----------|---------------------------|----------------------------|-------|
+| **Class** | `OnOffParameters` | `StatusParameters` | Main class renamed |
+| **Constructor** | `on_variable` | `status` | Model variable parameter |
+| **Constructor** | `previous_states` | `previous_status` | Initial state parameter |
+| **Parameter** | `effects_per_switch_on` | `effects_per_startup` | Startup costs/impacts |
+| **Parameter** | `effects_per_running_hour` | `effects_per_active_hour` | Operating costs/impacts |
+| **Parameter** | `on_hours_total_min` | `active_hours_min` | Minimum total operating hours |
+| **Parameter** | `on_hours_total_max` | `active_hours_max` | Maximum total operating hours |
+| **Parameter** | `consecutive_on_hours_min` | `min_uptime` | UC standard terminology |
+| **Parameter** | `consecutive_on_hours_max` | `max_uptime` | UC standard terminology |
+| **Parameter** | `consecutive_off_hours_min` | `min_downtime` | UC standard terminology |
+| **Parameter** | `consecutive_off_hours_max` | `max_downtime` | UC standard terminology |
+| **Parameter** | `switch_on_total_max` | `startup_limit` | Maximum number of startups |
+| **Parameter** | `force_switch_on` | `force_startup_tracking` | Force creation of startup variables |
+
+**Model Classes and Variables:**
+
+| Category | Old Name (OnOffModel) | New Name (StatusModel) | Notes |
+|----------|----------------------|------------------------|-------|
+| **Model Class** | `OnOffModel` | `StatusModel` | Feature model class |
+| **Variable** | `on` | `status` | Main binary state variable |
+| **Variable** | `switch_on` | `startup` | Startup event variable |
+| **Variable** | `switch_off` | `shutdown` | Shutdown event variable |
+| **Variable** | `switch_on_nr` | `startup_count` | Cumulative startup counter |
+| **Variable** | `on_hours_total` | `active_hours` | Total operating hours |
+| **Variable** | `consecutive_on_hours` | `uptime` | Consecutive active hours |
+| **Variable** | `consecutive_off_hours` | `downtime` | Consecutive inactive hours |
+| **Variable** | `off` | `inactive` | Deprecated - use `1 - status` instead |
+
+**Flow and Component API:**
+
+| Category | Old Name | New Name | Location |
+|----------|----------|----------|----------|
+| **Parameter** | `on_off_parameters` | `status_parameters` | `Flow.__init__()` |
+| **Parameter** | `on_off_parameters` | `status_parameters` | `Component.__init__()` |
+| **Property** | `flow.submodel.on_off` | `flow.submodel.status` | Flow submodel access |
+| **Property** | `component.submodel.on_off` | `component.submodel.status` | Component submodel access |
+
+**Internal Properties:**
+
+| Old Name | New Name |
+|----------|----------|
+| `use_switch_on` | `use_startup_tracking` |
+| `use_consecutive_on_hours` | `use_uptime_tracking` |
+| `use_consecutive_off_hours` | `use_downtime_tracking` |
+| `with_on_off` | `with_status` |
+| `previous_states` | `previous_status` |
+
+**Migration Guide**:
+
+Use find-and-replace to update your code with the mappings above. The functionality is identical - only naming has changed.
+
+**Important**: This is a complete renaming with no backwards compatibility. The change affects:
+- Constructor parameter names
+- Model variable names and property access
+- Results access patterns
+
+A partial backwards compatibility wrapper would be misleading, so we opted for a clean breaking change.
+
 ### ♻️ Changed
 
 ### 🗑️ Deprecated
 
@@ -28,7 +28,7 @@ Element labels must be unique across all types. See the [`FlowSystem` API refere
 
 - Have a `size` which, generally speaking, defines how much energy or material can be moved. Usually measured in MW, kW, m³/h, etc.
 - Have a `flow_rate`, which defines how fast energy or material is transported. Usually measured in MW, kW, m³/h, etc.
-- Have constraints to limit the flow-rate (min/max, total flow hours, on/off etc.)
+- Have constraints to limit the flow-rate (min/max, total flow hours, active/inactive status etc.)
 - Can have fixed profiles (for demands or renewable generation)
 - Can have [Effects](#effects) associated by their use (costs, emissions, labour, ...)
 
 
@@ -102,7 +102,7 @@ Scenarios within a period are **operationally independent**:
 - Each scenario has its own operational variables: $p(\text{t}_i, s_1)$ and $p(\text{t}_i, s_2)$ are independent
 - Scenarios cannot exchange energy, information, or resources
 - Storage states are separate: $c(\text{t}_i, s_1) \neq c(\text{t}_i, s_2)$
-- Binary states (on/off) are independent: $s(\text{t}_i, s_1)$ vs $s(\text{t}_i, s_2)$
+- Binary states (active/inactive) are independent: $s(\text{t}_i, s_1)$ vs $s(\text{t}_i, s_2)$
 
 Scenarios are connected **only through the objective function** via weights:
 
 
@@ -7,6 +7,7 @@
 **Example:**
 
 [`Flows`][flixopt.elements.Flow] have an attribute `effects_per_flow_hour` that defines the effect contribution per flow-hour:
+
 - Costs (€/kWh)
 - Emissions (kg CO₂/kWh)
 - Primary energy consumption (kWh_primary/kWh)
@@ -260,6 +261,7 @@ $$
 $$
 
 Where:
+
 - $\mathcal{S}$ is the set of scenarios
 - $w_s$ is the weight for scenario $s$ (typically scenario probability)
 - Periodic effects are **shared across scenarios**: $E_{\Omega,\text{per}}$ and $E_{\Phi,\text{per}}$ (same for all $s$)
@@ -280,6 +282,7 @@ $$
 $$
 
 Where:
+
 - $\mathcal{Y}$ is the set of periods (e.g., years)
 - $w_y$ is the weight for period $y$ (typically annual discount factor)
 - Each period $y$ has **independent** periodic and temporal effects (including penalty)
@@ -295,6 +298,7 @@ $$
 $$
 
 Where:
+
 - $\mathcal{S}$ is the set of scenarios
 - $\mathcal{Y}$ is the set of periods
 - $w_y$ is the period weight (for periodic effects)
 
@@ -23,8 +23,8 @@ $$
 $$
 
 
-This mathematical formulation can be extended by using [OnOffParameters](../features/OnOffParameters.md)
-to define the on/off state of the Flow, or by using [InvestParameters](../features/InvestParameters.md)
+This mathematical formulation can be extended by using [StatusParameters](../features/StatusParameters.md)
+to define the active/inactive state of the Flow, or by using [InvestParameters](../features/InvestParameters.md)
 to change the size of the Flow from a constant to an optimization variable.
 
 ---
@@ -34,7 +34,7 @@ to change the size of the Flow from a constant to an optimization variable.
 Flow formulation uses the following modeling patterns:
 
 - **[Scaled Bounds](../modeling-patterns/bounds-and-states.md#scaled-bounds)** - Basic flow rate bounds (equation $\eqref{eq:flow_rate}$)
-- **[Scaled Bounds with State](../modeling-patterns/bounds-and-states.md#scaled-bounds-with-state)** - When combined with [OnOffParameters](../features/OnOffParameters.md)
+- **[Scaled Bounds with State](../modeling-patterns/bounds-and-states.md#scaled-bounds-with-state)** - When combined with [StatusParameters](../features/StatusParameters.md)
 - **[Bounds with State](../modeling-patterns/bounds-and-states.md#bounds-with-state)** - Investment decisions with [InvestParameters](../features/InvestParameters.md)
 
 ---
@@ -44,19 +44,20 @@ Flow formulation uses the following modeling patterns:
 **Python Class:** [`Flow`][flixopt.elements.Flow]
 
 **Key Parameters:**
+
 - `size`: Flow size $\text{P}$ (can be fixed or variable with InvestParameters)
 - `relative_minimum`, `relative_maximum`: Relative bounds $\text{p}^{\text{L}}_{\text{rel}}, \text{p}^{\text{U}}_{\text{rel}}$
 - `effects_per_flow_hour`: Operational effects (costs, emissions, etc.)
 - `invest_parameters`: Optional investment modeling (see [InvestParameters](../features/InvestParameters.md))
-- `on_off_parameters`: Optional on/off operation (see [OnOffParameters](../features/OnOffParameters.md))
+- `status_parameters`: Optional active/inactive operation (see [StatusParameters](../features/StatusParameters.md))
 
 See the [`Flow`][flixopt.elements.Flow] API documentation for complete parameter list and usage examples.
 
 ---
 
 ## See Also
 
-- [OnOffParameters](../features/OnOffParameters.md) - Binary on/off operation
+- [StatusParameters](../features/StatusParameters.md) - Binary active/inactive operation
 - [InvestParameters](../features/InvestParameters.md) - Variable flow sizing
 - [Bus](../elements/Bus.md) - Flow balance constraints
 - [LinearConverter](../elements/LinearConverter.md) - Flow ratio constraints
 
@@ -53,6 +53,7 @@ Storage formulation uses the following modeling patterns:
 - **[Scaled Bounds](../modeling-patterns/bounds-and-states.md#scaled-bounds)** - For flow rate bounds relative to storage size
 
 When combined with investment parameters, storage can use:
+
 - **[Bounds with State](../modeling-patterns/bounds-and-states.md#bounds-with-state)** - Investment decisions (see [InvestParameters](../features/InvestParameters.md))
 
 ---
@@ -62,6 +63,7 @@ When combined with investment parameters, storage can use:
 **Python Class:** [`Storage`][flixopt.components.Storage]
 
 **Key Parameters:**
+
 - `capacity_in_flow_hours`: Storage capacity $\text{C}$
 - `relative_loss_per_hour`: Self-discharge rate $\dot{\text{c}}_\text{rel,loss}$
 - `initial_charge_state`: Initial charge $c(\text{t}_0)$
 
@@ -15,6 +15,7 @@ v_\text{invest} = s_\text{invest} \cdot \text{size}_\text{fixed}
 $$
 
 With:
+
 - $v_\text{invest}$ being the resulting investment size
 - $s_\text{invest} \in \{0, 1\}$ being the binary investment decision
 - $\text{size}_\text{fixed}$ being the predefined component size
@@ -34,6 +35,7 @@ s_\text{invest} \cdot \text{size}_\text{min} \leq v_\text{invest} \leq s_\text{i
 $$
 
 With:
+
 - $v_\text{invest}$ being the investment size variable (continuous)
 - $s_\text{invest} \in \{0, 1\}$ being the binary investment decision
 - $\text{size}_\text{min}$ being the minimum investment size (if investing)
@@ -80,6 +82,7 @@ E_{e,\text{fix}} = s_\text{invest} \cdot \text{fix}_e
 $$
 
 With:
+
 - $E_{e,\text{fix}}$ being the fixed contribution to effect $e$
 - $\text{fix}_e$ being the fixed effect value (e.g., fixed installation cost)
 
@@ -99,6 +102,7 @@ E_{e,\text{spec}} = v_\text{invest} \cdot \text{spec}_e
 $$
 
 With:
+
 - $E_{e,\text{spec}}$ being the size-dependent contribution to effect $e$
 - $\text{spec}_e$ being the specific effect value per unit size (e.g., €/kW)
 
@@ -123,6 +127,7 @@ v_\text{invest} = \sum_{k=1}^{K} \lambda_k \cdot v_k
 $$
 
 With:
+
 - $E_{e,\text{pw}}$ being the piecewise contribution to effect $e$
 - $\lambda_k$ being the piecewise lambda variables (see [Piecewise](../features/Piecewise.md))
 - $r_{e,k}$ being the effect rate at piece $k$
@@ -146,6 +151,7 @@ E_{e,\text{retirement}} = (1 - s_\text{invest}) \cdot \text{retirement}_e
 $$
 
 With:
+
 - $E_{e,\text{retirement}}$ being the retirement contribution to effect $e$
 - $\text{retirement}_e$ being the retirement effect value
 
@@ -210,6 +216,7 @@ $$\label{eq:annualization}
 $$
 
 With:
+
 - $\text{cost}_\text{capital}$ being the upfront investment cost
 - $r$ being the discount rate
 - $n$ being the equipment lifetime in years
@@ -226,6 +233,7 @@ $$
 **Python Class:** [`InvestParameters`][flixopt.interface.InvestParameters]
 
 **Key Parameters:**
+
 - `fixed_size`: For binary investments (mutually exclusive with continuous sizing)
 - `minimum_size`, `maximum_size`: For continuous sizing
 - `mandatory`: Whether investment is required (default: `False`)