diff --git a/web/src/components/CaseBuilder/Buses.test.ts b/web/src/components/CaseBuilder/Buses.test.ts
index bc74a3b..21fe0a7 100644
--- a/web/src/components/CaseBuilder/Buses.test.ts
+++ b/web/src/components/CaseBuilder/Buses.test.ts
@@ -7,7 +7,7 @@
 import assert from "node:assert";
 import { BusesColumnSpec, generateBusesData } from "./Buses";
 import { generateCsv, parseCsv } from "../Common/Forms/DataTable";
-import { TEST_DATA_1 } from "../../core/fixtures.test";
+import { TEST_DATA_1 } from "../../core/Data/fixtures.test";
 
 test("generate CSV", () => {
   const [data, columns] = generateBusesData(TEST_DATA_1);
diff --git a/web/src/components/CaseBuilder/Buses.tsx b/web/src/components/CaseBuilder/Buses.tsx
index f46c4ae..81ea25e 100644
--- a/web/src/components/CaseBuilder/Buses.tsx
+++ b/web/src/components/CaseBuilder/Buses.tsx
@@ -14,7 +14,7 @@ import {
 import { offerDownload } from "../Common/io";
 import FileUploadElement from "../Common/Buttons/FileUploadElement";
 import { useRef } from "react";
-import { ValidationError } from "../../core/Validation/validate";
+import { ValidationError } from "../../core/Data/validate";
 import DataTable, {
   ColumnSpec,
   generateCsv,
@@ -23,7 +23,6 @@ import DataTable, {
   parseCsv,
 } from "../Common/Forms/DataTable";
 
-import { UnitCommitmentScenario } from "../../core/fixtures";
 import { ColumnDefinition } from "tabulator-tables";
 import {
   changeBusData,
@@ -32,6 +31,7 @@ import {
   renameBus,
 } from "../../core/Operations/busOps";
 import { CaseBuilderSectionProps } from "./CaseBuilder";
+import { UnitCommitmentScenario } from "../../core/Data/types";
 
 export const BusesColumnSpec: ColumnSpec[] = [
   {
diff --git a/web/src/components/CaseBuilder/CaseBuilder.tsx b/web/src/components/CaseBuilder/CaseBuilder.tsx
index 1650953..188982a 100644
--- a/web/src/components/CaseBuilder/CaseBuilder.tsx
+++ b/web/src/components/CaseBuilder/CaseBuilder.tsx
@@ -7,23 +7,20 @@
 import Header from "./Header";
 import Parameters from "./Parameters";
 import BusesComponent from "./Buses";
-import {
-  BLANK_SCENARIO,
-  TEST_SCENARIO,
-  UnitCommitmentScenario,
-} from "../../core/fixtures";
+import { BLANK_SCENARIO, TEST_SCENARIO } from "../../core/Data/fixtures";
 
 import "tabulator-tables/dist/css/tabulator.min.css";
 import "../Common/Forms/Tables.css";
 import { useState } from "react";
 import Footer from "./Footer";
-import { validate } from "../../core/Validation/validate";
+import { validate } from "../../core/Data/validate";
 import { offerDownload } from "../Common/io";
 import { preprocess } from "../../core/Operations/preprocessing";
 import Toast from "../Common/Forms/Toast";
 import ProfiledUnitsComponent from "./ProfiledUnits";
 import ThermalUnitsComponent from "./ThermalUnits";
 import TransmissionLinesComponent from "./TransmissionLines";
+import { UnitCommitmentScenario } from "../../core/Data/types";
 
 export interface CaseBuilderSectionProps {
   scenario: UnitCommitmentScenario;
diff --git a/web/src/components/CaseBuilder/Header.tsx b/web/src/components/CaseBuilder/Header.tsx
index 69e432b..9573edf 100644
--- a/web/src/components/CaseBuilder/Header.tsx
+++ b/web/src/components/CaseBuilder/Header.tsx
@@ -6,9 +6,9 @@
 
 import styles from "./Header.module.css";
 import SiteHeaderButton from "../Common/Buttons/SiteHeaderButton";
-import { UnitCommitmentScenario } from "../../core/fixtures";
 import { useRef } from "react";
 import FileUploadElement from "../Common/Buttons/FileUploadElement";
+import { UnitCommitmentScenario } from "../../core/Data/types";
 
 interface HeaderProps {
   onClear: () => void;
diff --git a/web/src/components/CaseBuilder/Parameters.tsx b/web/src/components/CaseBuilder/Parameters.tsx
index f0009c8..20092dc 100644
--- a/web/src/components/CaseBuilder/Parameters.tsx
+++ b/web/src/components/CaseBuilder/Parameters.tsx
@@ -7,12 +7,12 @@
 import SectionHeader from "../Common/SectionHeader/SectionHeader";
 import Form from "../Common/Forms/Form";
 import TextInputRow from "../Common/Forms/TextInputRow";
-import { UnitCommitmentScenario } from "../../core/fixtures";
 import {
   changeParameter,
   changeTimeHorizon,
   changeTimeStep,
 } from "../../core/Operations/parameterOps";
+import { UnitCommitmentScenario } from "../../core/Data/types";
 
 interface ParametersProps {
   scenario: UnitCommitmentScenario;
diff --git a/web/src/components/CaseBuilder/ProfiledUnits.test.ts b/web/src/components/CaseBuilder/ProfiledUnits.test.ts
index 81c63f7..7119d94 100644
--- a/web/src/components/CaseBuilder/ProfiledUnits.test.ts
+++ b/web/src/components/CaseBuilder/ProfiledUnits.test.ts
@@ -13,12 +13,12 @@ import {
   parseProfiledUnitsCsv,
   ProfiledUnitsColumnSpec,
 } from "./ProfiledUnits";
-import { TEST_DATA_1 } from "../../core/fixtures.test";
+import { TEST_DATA_1 } from "../../core/Data/fixtures.test";
 import assert from "node:assert";
 import {
   getProfiledGenerators,
   getThermalGenerators,
-} from "../../core/fixtures";
+} from "../../core/Data/types";
 
 test("parse CSV", () => {
   const csvContents =
diff --git a/web/src/components/CaseBuilder/ProfiledUnits.tsx b/web/src/components/CaseBuilder/ProfiledUnits.tsx
index 4029bb6..d4aeb51 100644
--- a/web/src/components/CaseBuilder/ProfiledUnits.tsx
+++ b/web/src/components/CaseBuilder/ProfiledUnits.tsx
@@ -18,11 +18,6 @@ import DataTable, {
   generateTableData,
   parseCsv,
 } from "../Common/Forms/DataTable";
-import {
-  getProfiledGenerators,
-  getThermalGenerators,
-  UnitCommitmentScenario,
-} from "../../core/fixtures";
 import { ColumnDefinition } from "tabulator-tables";
 import { offerDownload } from "../Common/io";
 import FileUploadElement from "../Common/Buttons/FileUploadElement";
@@ -33,8 +28,13 @@ import {
   deleteGenerator,
   renameGenerator,
 } from "../../core/Operations/generatorOps";
-import { ValidationError } from "../../core/Validation/validate";
+import { ValidationError } from "../../core/Data/validate";
 import { CaseBuilderSectionProps } from "./CaseBuilder";
+import {
+  getProfiledGenerators,
+  getThermalGenerators,
+  UnitCommitmentScenario,
+} from "../../core/Data/types";
 
 export const ProfiledUnitsColumnSpec: ColumnSpec[] = [
   {
diff --git a/web/src/components/CaseBuilder/ThermalUnits.test.ts b/web/src/components/CaseBuilder/ThermalUnits.test.ts
index a5b4a02..b89425e 100644
--- a/web/src/components/CaseBuilder/ThermalUnits.test.ts
+++ b/web/src/components/CaseBuilder/ThermalUnits.test.ts
@@ -10,7 +10,7 @@ import {
   generateTableColumns,
   generateTableData,
 } from "../Common/Forms/DataTable";
-import { TEST_DATA_1 } from "../../core/fixtures.test";
+import { TEST_DATA_1 } from "../../core/Data/fixtures.test";
 import {
   generateThermalUnitsData,
   parseThermalUnitsCsv,
@@ -20,7 +20,7 @@ import assert from "node:assert";
 import {
   getProfiledGenerators,
   getThermalGenerators,
-} from "../../core/fixtures";
+} from "../../core/Data/types";
 
 test("generateTableColumns", () => {
   const columns = generateTableColumns(TEST_DATA_1, ThermalUnitsColumnSpec);
diff --git a/web/src/components/CaseBuilder/ThermalUnits.tsx b/web/src/components/CaseBuilder/ThermalUnits.tsx
index e7af112..a1aff04 100644
--- a/web/src/components/CaseBuilder/ThermalUnits.tsx
+++ b/web/src/components/CaseBuilder/ThermalUnits.tsx
@@ -14,7 +14,7 @@ import DataTable, {
 import { CaseBuilderSectionProps } from "./CaseBuilder";
 import { useRef } from "react";
 import FileUploadElement from "../Common/Buttons/FileUploadElement";
-import { ValidationError } from "../../core/Validation/validate";
+import { ValidationError } from "../../core/Data/validate";
 import SectionHeader from "../Common/SectionHeader/SectionHeader";
 import SectionButton from "../Common/Buttons/SectionButton";
 import {
@@ -22,11 +22,6 @@ import {
   faPlus,
   faUpload,
 } from "@fortawesome/free-solid-svg-icons";
-import {
-  getProfiledGenerators,
-  getThermalGenerators,
-  UnitCommitmentScenario,
-} from "../../core/fixtures";
 import { ColumnDefinition } from "tabulator-tables";
 import { offerDownload } from "../Common/io";
 import {
@@ -35,6 +30,11 @@ import {
   deleteGenerator,
   renameGenerator,
 } from "../../core/Operations/generatorOps";
+import {
+  getProfiledGenerators,
+  getThermalGenerators,
+  UnitCommitmentScenario,
+} from "../../core/Data/types";
 
 export const ThermalUnitsColumnSpec: ColumnSpec[] = [
   {
diff --git a/web/src/components/CaseBuilder/TransmissionLines.tsx b/web/src/components/CaseBuilder/TransmissionLines.tsx
index 7291743..39c1300 100644
--- a/web/src/components/CaseBuilder/TransmissionLines.tsx
+++ b/web/src/components/CaseBuilder/TransmissionLines.tsx
@@ -18,11 +18,10 @@ import DataTable, {
   generateTableData,
   parseCsv,
 } from "../Common/Forms/DataTable";
-import { UnitCommitmentScenario } from "../../core/fixtures";
 import { ColumnDefinition } from "tabulator-tables";
 import FileUploadElement from "../Common/Buttons/FileUploadElement";
 import { useRef } from "react";
-import { ValidationError } from "../../core/Validation/validate";
+import { ValidationError } from "../../core/Data/validate";
 import { CaseBuilderSectionProps } from "./CaseBuilder";
 import {
   changeTransmissionLineData,
@@ -31,6 +30,7 @@ import {
   renameTransmissionLine,
 } from "../../core/Operations/transmissionOps";
 import { offerDownload } from "../Common/io";
+import { UnitCommitmentScenario } from "../../core/Data/types";
 
 export const TransmissionLinesColumnSpec: ColumnSpec[] = [
   {
diff --git a/web/src/components/Common/Forms/DataTable.tsx b/web/src/components/Common/Forms/DataTable.tsx
index 67b652c..962fa36 100644
--- a/web/src/components/Common/Forms/DataTable.tsx
+++ b/web/src/components/Common/Forms/DataTable.tsx
@@ -10,10 +10,10 @@ import {
   ColumnDefinition,
   TabulatorFull as Tabulator,
 } from "tabulator-tables";
-import { ValidationError } from "../../../core/Validation/validate";
-import { UnitCommitmentScenario } from "../../../core/fixtures";
+import { ValidationError } from "../../../core/Data/validate";
 import Papa from "papaparse";
 import { parseBool, parseNumber } from "../../../core/Operations/commonOps";
+import { UnitCommitmentScenario } from "../../../core/Data/types";
 
 export interface ColumnSpec {
   title: string;
diff --git a/web/src/components/Common/Forms/TextInputRow.tsx b/web/src/components/Common/Forms/TextInputRow.tsx
index fd513b9..854e315 100644
--- a/web/src/components/Common/Forms/TextInputRow.tsx
+++ b/web/src/components/Common/Forms/TextInputRow.tsx
@@ -7,7 +7,7 @@
 import formStyles from "./Form.module.css";
 import HelpButton from "../Buttons/HelpButton";
 import React, { useRef, useState } from "react";
-import { ValidationError } from "../../../core/Validation/validate";
+import { ValidationError } from "../../../core/Data/validate";
 
 interface TextInputRowProps {
   label: string;
diff --git a/web/src/core/fixtures.test.ts b/web/src/core/Data/fixtures.test.ts
similarity index 88%
rename from web/src/core/fixtures.test.ts
rename to web/src/core/Data/fixtures.test.ts
index 916ae9a..fdb248f 100644
--- a/web/src/core/fixtures.test.ts
+++ b/web/src/core/Data/fixtures.test.ts
@@ -1,4 +1,10 @@
-import { UnitCommitmentScenario } from "./fixtures";
+/*
+ * UnitCommitment.jl: Optimization Package for Security-Constrained Unit Commitment
+ * Copyright (C) 2020-2025, UChicago Argonne, LLC. All rights reserved.
+ * Released under the modified BSD license. See COPYING.md for more details.
+ */
+
+import { UnitCommitmentScenario } from "./types";
 
 export const TEST_DATA_1: UnitCommitmentScenario = {
   Parameters: {
diff --git a/web/src/core/fixtures.tsx b/web/src/core/Data/fixtures.tsx
similarity index 70%
rename from web/src/core/fixtures.tsx
rename to web/src/core/Data/fixtures.tsx
index dcd3b66..ba2e00b 100644
--- a/web/src/core/fixtures.tsx
+++ b/web/src/core/Data/fixtures.tsx
@@ -4,86 +4,12 @@
  * Released under the modified BSD license. See COPYING.md for more details.
  */
 
+import { UnitCommitmentScenario } from "./types";
+
 export interface Buses {
   [busName: string]: { "Load (MW)": number[] };
 }
 
-export interface Generators {
-  [name: string]: ProfiledUnit | ThermalUnit;
-}
-
-export interface ProfiledUnit {
-  Bus: string;
-  Type: "Profiled";
-  "Minimum power (MW)": number[];
-  "Maximum power (MW)": number[];
-  "Cost ($/MW)": number;
-}
-
-export interface ThermalUnit {
-  Bus: string;
-  Type: "Thermal";
-  "Production cost curve (MW)": number[];
-  "Production cost curve ($)": number[];
-  "Startup costs ($)": number[];
-  "Startup delays (h)": number[];
-  "Ramp up limit (MW)": number | "";
-  "Ramp down limit (MW)": number | "";
-  "Startup limit (MW)": number | "";
-  "Shutdown limit (MW)": number | "";
-  "Minimum downtime (h)": number;
-  "Minimum uptime (h)": number;
-  "Initial status (h)": number;
-  "Initial power (MW)": number;
-  "Must run?": boolean;
-}
-
-export interface TransmissionLine {
-  "Source bus": string;
-  "Target bus": string;
-  "Susceptance (S)": number;
-  "Normal flow limit (MW)": number;
-  "Emergency flow limit (MW)": number;
-  "Flow limit penalty ($/MW)": number;
-}
-
-export interface UnitCommitmentScenario {
-  Parameters: {
-    Version: string;
-    "Power balance penalty ($/MW)": number;
-    "Time horizon (h)": number;
-    "Time step (min)": number;
-  };
-  Buses: Buses;
-  Generators: Generators;
-  "Transmission lines": {
-    [name: string]: TransmissionLine;
-  };
-}
-
-const getTypedGenerators = <T extends any>(
-  scenario: UnitCommitmentScenario,
-  type: string,
-): {
-  [key: string]: T;
-} => {
-  const selected: { [key: string]: T } = {};
-  for (const [name, gen] of Object.entries(scenario.Generators)) {
-    if (gen["Type"] === type) selected[name] = gen as T;
-  }
-  return selected;
-};
-
-export const getProfiledGenerators = (
-  scenario: UnitCommitmentScenario,
-): { [key: string]: ProfiledUnit } =>
-  getTypedGenerators<ProfiledUnit>(scenario, "Profiled");
-
-export const getThermalGenerators = (
-  scenario: UnitCommitmentScenario,
-): { [key: string]: ThermalUnit } =>
-  getTypedGenerators<ThermalUnit>(scenario, "Thermal");
-
 export const BLANK_SCENARIO: UnitCommitmentScenario = {
   Parameters: {
     Version: "0.4",
diff --git a/web/src/core/Data/migrate.test.ts b/web/src/core/Data/migrate.test.ts
new file mode 100644
index 0000000..84b248b
--- /dev/null
+++ b/web/src/core/Data/migrate.test.ts
@@ -0,0 +1,34 @@
+/*
+ * UnitCommitment.jl: Optimization Package for Security-Constrained Unit Commitment
+ * Copyright (C) 2020-2025, UChicago Argonne, LLC. All rights reserved.
+ * Released under the modified BSD license. See COPYING.md for more details.
+ */
+
+import assert from "node:assert";
+import fs from "node:fs";
+import pako from "pako";
+import { migrateToV03, migrateToV04 } from "./migrate";
+
+function readJsonGz(filename: string) {
+  const compressedData = fs.readFileSync(filename);
+  const decompressedData = pako.inflate(compressedData, { to: "string" });
+  return JSON.parse(decompressedData);
+}
+
+test("migrateToV03", () => {
+  const jsonData = readJsonGz("../test/fixtures/ucjl-0.2.json.gz");
+  migrateToV03(jsonData);
+  assert.deepEqual(jsonData.Reserves, {
+    r1: {
+      "Amount (MW)": 100,
+      "Shortfall penalty ($/MW)": 1000,
+      Type: "spinning",
+    },
+  });
+});
+
+test("migrateToV04", () => {
+  const jsonData = readJsonGz("../test/fixtures/ucjl-0.3.json.gz");
+  migrateToV04(jsonData);
+  assert.equal(jsonData.Generators["g1"].Type, "Thermal");
+});
diff --git a/web/src/core/Data/migrate.ts b/web/src/core/Data/migrate.ts
new file mode 100644
index 0000000..3c450d2
--- /dev/null
+++ b/web/src/core/Data/migrate.ts
@@ -0,0 +1,56 @@
+/*
+ * UnitCommitment.jl: Optimization Package for Security-Constrained Unit Commitment
+ * Copyright (C) 2020-2025, UChicago Argonne, LLC. All rights reserved.
+ * Released under the modified BSD license. See COPYING.md for more details.
+ */
+
+import { ValidationError } from "./validate";
+
+export const migrate = (json: any): ValidationError | null => {
+  const version = json.Parameters?.Version;
+  if (!version) {
+    return {
+      message:
+        "The provided input file cannot be loaded because it does not " +
+        "specify what version of UnitCommitment.jl it was written for.",
+    };
+  }
+  if (!["0.2", "0.3", "0.4"].includes(version)) {
+    return { message: `Unsupported file version: ${version}` };
+  }
+  if (version < "0.3") migrateToV03(json);
+  if (version < "0.4") migrateToV04(json);
+  json.Parameters.Version = "0.4";
+  return null;
+};
+
+export const migrateToV03 = (json: any): void => {
+  if (json.Reserves && json.Reserves["Spinning (MW)"] != null) {
+    const amount = json.Reserves["Spinning (MW)"];
+    json.Reserves = {
+      r1: {
+        Type: "spinning",
+        "Amount (MW)": amount,
+      },
+    };
+    if (json.Generators) {
+      for (const genName in json.Generators) {
+        const gen = json.Generators[genName];
+        if (gen["Provides spinning reserves?"] === true) {
+          gen["Reserve eligibility"] = ["r1"];
+        }
+      }
+    }
+  }
+};
+
+export const migrateToV04 = (json: any): void => {
+  if (json.Generators) {
+    for (const genName in json.Generators) {
+      const gen = json.Generators[genName];
+      if (gen.Type == null) {
+        gen.Type = "Thermal";
+      }
+    }
+  }
+};
diff --git a/web/src/core/Validation/schema.ts b/web/src/core/Data/schema.ts
similarity index 100%
rename from web/src/core/Validation/schema.ts
rename to web/src/core/Data/schema.ts
diff --git a/web/src/core/Data/types.tsx b/web/src/core/Data/types.tsx
new file mode 100644
index 0000000..ad3a237
--- /dev/null
+++ b/web/src/core/Data/types.tsx
@@ -0,0 +1,81 @@
+/*
+ * UnitCommitment.jl: Optimization Package for Security-Constrained Unit Commitment
+ * Copyright (C) 2020-2025, UChicago Argonne, LLC. All rights reserved.
+ * Released under the modified BSD license. See COPYING.md for more details.
+ */
+
+import { Buses } from "./fixtures";
+
+export interface Generators {
+  [name: string]: ProfiledUnit | ThermalUnit;
+}
+
+export interface ProfiledUnit {
+  Bus: string;
+  Type: "Profiled";
+  "Minimum power (MW)": number[];
+  "Maximum power (MW)": number[];
+  "Cost ($/MW)": number;
+}
+
+export interface ThermalUnit {
+  Bus: string;
+  Type: "Thermal";
+  "Production cost curve (MW)": number[];
+  "Production cost curve ($)": number[];
+  "Startup costs ($)": number[];
+  "Startup delays (h)": number[];
+  "Ramp up limit (MW)": number | "";
+  "Ramp down limit (MW)": number | "";
+  "Startup limit (MW)": number | "";
+  "Shutdown limit (MW)": number | "";
+  "Minimum downtime (h)": number;
+  "Minimum uptime (h)": number;
+  "Initial status (h)": number;
+  "Initial power (MW)": number;
+  "Must run?": boolean;
+}
+
+export interface TransmissionLine {
+  "Source bus": string;
+  "Target bus": string;
+  "Susceptance (S)": number;
+  "Normal flow limit (MW)": number;
+  "Emergency flow limit (MW)": number;
+  "Flow limit penalty ($/MW)": number;
+}
+
+export interface UnitCommitmentScenario {
+  Parameters: {
+    Version: string;
+    "Power balance penalty ($/MW)": number;
+    "Time horizon (h)": number;
+    "Time step (min)": number;
+  };
+  Buses: Buses;
+  Generators: Generators;
+  "Transmission lines": {
+    [name: string]: TransmissionLine;
+  };
+}
+
+const getTypedGenerators = <T extends any>(
+  scenario: UnitCommitmentScenario,
+  type: string,
+): {
+  [key: string]: T;
+} => {
+  const selected: { [key: string]: T } = {};
+  for (const [name, gen] of Object.entries(scenario.Generators)) {
+    if (gen["Type"] === type) selected[name] = gen as T;
+  }
+  return selected;
+};
+export const getProfiledGenerators = (
+  scenario: UnitCommitmentScenario,
+): { [key: string]: ProfiledUnit } =>
+  getTypedGenerators<ProfiledUnit>(scenario, "Profiled");
+export const getThermalGenerators = (
+  scenario: UnitCommitmentScenario,
+): { [key: string]: ThermalUnit } =>
+  getTypedGenerators<ThermalUnit>(scenario, "Thermal");
diff --git a/web/src/core/Validation/validate.ts b/web/src/core/Data/validate.ts
similarity index 100%
rename from web/src/core/Validation/validate.ts
rename to web/src/core/Data/validate.ts
diff --git a/web/src/core/Operations/busOps.test.ts b/web/src/core/Operations/busOps.test.ts
index 09c431b..590c708 100644
--- a/web/src/core/Operations/busOps.test.ts
+++ b/web/src/core/Operations/busOps.test.ts
@@ -6,7 +6,7 @@
 
 import { changeBusData, createBus, deleteBus, renameBus } from "./busOps";
 import assert from "node:assert";
-import { TEST_DATA_1 } from "../fixtures.test";
+import { TEST_DATA_1 } from "../Data/fixtures.test";
 
 test("createBus", () => {
   const newScenario = createBus(TEST_DATA_1);
diff --git a/web/src/core/Operations/busOps.ts b/web/src/core/Operations/busOps.ts
index db98f15..3a51a2b 100644
--- a/web/src/core/Operations/busOps.ts
+++ b/web/src/core/Operations/busOps.ts
@@ -4,8 +4,8 @@
  * Released under the modified BSD license. See COPYING.md for more details.
  */
 
-import { Buses, UnitCommitmentScenario } from "../fixtures";
-import { ValidationError } from "../Validation/validate";
+import { Buses } from "../Data/fixtures";
+import { ValidationError } from "../Data/validate";
 import { generateTimeslots } from "../../components/Common/Forms/DataTable";
 import {
   changeData,
@@ -13,6 +13,7 @@ import {
   renameItemInObject,
 } from "./commonOps";
 import { BusesColumnSpec } from "../../components/CaseBuilder/Buses";
+import { UnitCommitmentScenario } from "../Data/types";
 
 export const createBus = (scenario: UnitCommitmentScenario) => {
   const name = generateUniqueName(scenario.Buses, "b");
diff --git a/web/src/core/Operations/commonOps.ts b/web/src/core/Operations/commonOps.ts
index e3af76c..ff0f99e 100644
--- a/web/src/core/Operations/commonOps.ts
+++ b/web/src/core/Operations/commonOps.ts
@@ -4,9 +4,9 @@
  * Released under the modified BSD license. See COPYING.md for more details.
  */
 
-import { ValidationError } from "../Validation/validate";
-import { UnitCommitmentScenario } from "../fixtures";
+import { ValidationError } from "../Data/validate";
 import { ColumnSpec } from "../../components/Common/Forms/DataTable";
+import { UnitCommitmentScenario } from "../Data/types";
 
 export const renameItemInObject = <T>(
   oldName: string,
diff --git a/web/src/core/Operations/generatorOps.test.ts b/web/src/core/Operations/generatorOps.test.ts
index 5664518..ecb1f12 100644
--- a/web/src/core/Operations/generatorOps.test.ts
+++ b/web/src/core/Operations/generatorOps.test.ts
@@ -4,7 +4,7 @@
  * Released under the modified BSD license. See COPYING.md for more details.
  */
 
-import { TEST_DATA_1, TEST_DATA_BLANK } from "../fixtures.test";
+import { TEST_DATA_1, TEST_DATA_BLANK } from "../Data/fixtures.test";
 import assert from "node:assert";
 import {
   changeProfiledUnitData,
@@ -14,7 +14,7 @@ import {
   deleteGenerator,
   renameGenerator,
 } from "./generatorOps";
-import { ValidationError } from "../Validation/validate";
+import { ValidationError } from "../Data/validate";
 
 test("createProfiledUnit", () => {
   const [newScenario, err] = createProfiledUnit(TEST_DATA_1);
diff --git a/web/src/core/Operations/generatorOps.ts b/web/src/core/Operations/generatorOps.ts
index 56fef26..1e828cd 100644
--- a/web/src/core/Operations/generatorOps.ts
+++ b/web/src/core/Operations/generatorOps.ts
@@ -4,9 +4,8 @@
  * Released under the modified BSD license. See COPYING.md for more details.
  */
 
-import { Generators, UnitCommitmentScenario } from "../fixtures";
 import { generateTimeslots } from "../../components/Common/Forms/DataTable";
-import { ValidationError } from "../Validation/validate";
+import { ValidationError } from "../Data/validate";
 import {
   assertBusesNotEmpty,
   changeData,
@@ -15,6 +14,7 @@ import {
 } from "./commonOps";
 import { ProfiledUnitsColumnSpec } from "../../components/CaseBuilder/ProfiledUnits";
 import { ThermalUnitsColumnSpec } from "../../components/CaseBuilder/ThermalUnits";
+import { Generators, UnitCommitmentScenario } from "../Data/types";
 
 export const createProfiledUnit = (
   scenario: UnitCommitmentScenario,
diff --git a/web/src/core/Operations/parameterOps.test.ts b/web/src/core/Operations/parameterOps.test.ts
index 098007c..d3806c1 100644
--- a/web/src/core/Operations/parameterOps.test.ts
+++ b/web/src/core/Operations/parameterOps.test.ts
@@ -10,7 +10,7 @@ import {
   evaluatePwlFunction,
 } from "./parameterOps";
 import assert from "node:assert";
-import { TEST_DATA_1, TEST_DATA_2 } from "../fixtures.test";
+import { TEST_DATA_1, TEST_DATA_2 } from "../Data/fixtures.test";
 
 test("changeTimeHorizon: Shrink 1", () => {
   const [newScenario, err] = changeTimeHorizon(TEST_DATA_1, "3");
diff --git a/web/src/core/Operations/parameterOps.ts b/web/src/core/Operations/parameterOps.ts
index 91fe415..21a8214 100644
--- a/web/src/core/Operations/parameterOps.ts
+++ b/web/src/core/Operations/parameterOps.ts
@@ -4,8 +4,9 @@
  * Released under the modified BSD license. See COPYING.md for more details.
  */
 
-import { Buses, UnitCommitmentScenario } from "../fixtures";
-import { ValidationError } from "../Validation/validate";
+import { Buses } from "../Data/fixtures";
+import { ValidationError } from "../Data/validate";
+import { UnitCommitmentScenario } from "../Data/types";
 
 export const changeTimeHorizon = (
   scenario: UnitCommitmentScenario,
diff --git a/web/src/core/Operations/preprocessing.ts b/web/src/core/Operations/preprocessing.ts
index ccc0a0e..e66d571 100644
--- a/web/src/core/Operations/preprocessing.ts
+++ b/web/src/core/Operations/preprocessing.ts
@@ -6,7 +6,7 @@
  * Released under the modified BSD license. See COPYING.md for more details.
  */
 
-import { validate } from "../Validation/validate";
+import { validate } from "../Data/validate";
 
 export const preprocess = (data) => {
   // Make a copy of the original data
diff --git a/web/src/core/Operations/transmissionOps.test.ts b/web/src/core/Operations/transmissionOps.test.ts
index 1300e2c..65abdb5 100644
--- a/web/src/core/Operations/transmissionOps.test.ts
+++ b/web/src/core/Operations/transmissionOps.test.ts
@@ -4,7 +4,7 @@
  * Released under the modified BSD license. See COPYING.md for more details.
  */
 
-import { TEST_DATA_1 } from "../fixtures.test";
+import { TEST_DATA_1 } from "../Data/fixtures.test";
 import assert from "node:assert";
 import {
   changeTransmissionLineData,
@@ -12,7 +12,7 @@ import {
   deleteTransmissionLine,
   renameTransmissionLine,
 } from "./transmissionOps";
-import { ValidationError } from "../Validation/validate";
+import { ValidationError } from "../Data/validate";
 
 test("createTransmissionLine", () => {
   const [newScenario, err] = createTransmissionLine(TEST_DATA_1);
diff --git a/web/src/core/Operations/transmissionOps.ts b/web/src/core/Operations/transmissionOps.ts
index 6e90f21..0e55707 100644
--- a/web/src/core/Operations/transmissionOps.ts
+++ b/web/src/core/Operations/transmissionOps.ts
@@ -4,15 +4,15 @@
  * Released under the modified BSD license. See COPYING.md for more details.
  */
 
-import { TransmissionLine, UnitCommitmentScenario } from "../fixtures";
 import {
   assertBusesNotEmpty,
   changeData,
   generateUniqueName,
   renameItemInObject,
 } from "./commonOps";
-import { ValidationError } from "../Validation/validate";
+import { ValidationError } from "../Data/validate";
 import { TransmissionLinesColumnSpec } from "../../components/CaseBuilder/TransmissionLines";
+import { TransmissionLine, UnitCommitmentScenario } from "../Data/types";
 
 export const createTransmissionLine = (
   scenario: UnitCommitmentScenario,