diff --git a/.gitignore b/.gitignore
index 02551b4..80bc72c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,3 +2,4 @@ node_modules
 dist
 .env
 .idea
+.dockerignore
diff --git a/src/datasources/db/participantAPI.ts b/src/datasources/db/participantAPI.ts
index 311ba26..270ec09 100644
--- a/src/datasources/db/participantAPI.ts
+++ b/src/datasources/db/participantAPI.ts
@@ -130,7 +130,7 @@ export class ParticipantAPI extends DataSource {
     }
 
     async engagementTypes (offset?: number, limit?: number) {
-        return await DBUtils.getAllEntity(this.connection, Engagement, 'e', offset, limit);
+        return await DBUtils.getAllEntity(this.connection, EngagementType, 'et', offset, limit);
     }
 
     async engagementTypeByEngagementId (id: number) {
@@ -170,6 +170,7 @@ export class ParticipantAPI extends DataSource {
      * @param participant to be created
      */
     async createParticipant (participant: any) {
+        genDateRange(participant);
         let inserts: any;
         await this.connection.transaction(async (entityManager: EntityManager) => {
             inserts = await entityManager.getRepository(Participant)
@@ -201,8 +202,9 @@ export class ParticipantAPI extends DataSource {
         delete participant.keepLock;
         await this.connection.transaction(async (entityManager: EntityManager) => {
             if (await LockUtils.isLocked(entityManager, Participant, 'p', participant.id, userId)) {
-                throw new GraphQLError('Participant is locked by another user');
+                throw new UserInputError('Attempting to update locked resource');
             }
+            genDateRange(participant);
             const workshops = participant.workshopIds;
             delete participant.workshopIds;
             await ActionLogger.log(entityManager, Participant, 'p', participant, userId);
@@ -212,6 +214,17 @@ export class ParticipantAPI extends DataSource {
                 .set({ ...participant })
                 .where('id = :id', { id: participant.id })
                 .execute().then(value => { if (value.affected !== 1) { throw new UserInputError('ID not found'); } });
+            // check for engagements before or after dateRange
+            const engagements = await entityManager.getRepository(Engagement)
+                .createQueryBuilder('e')
+                .select()
+                .where('e."participantId" = :pid', { pid: participant.id })
+                .andWhere('not :pdr @> e."dateRange"', { pdr: participant.dateRange })
+                .getMany();
+            if (engagements.length !== 0) {
+                throw new UserInputError('Engagements with ids: ' + engagements.map((e) => { return `${e.id} ,`; }) + ' are are outside of dataRange');
+            }
+            // add and remove workshop relations
             workshops && await entityManager.getRepository(Participant)
                 .createQueryBuilder('w')
                 .relation(Participant, 'workshopIds')
@@ -241,6 +254,16 @@ export class ParticipantAPI extends DataSource {
             if (overlapping.length > 0) {
                 throw new UserInputError('Engagements with ids: ' + overlapping.map((e) => { return e.id + ', '; }) + 'are overlapping');
             }
+            // check if participant is active
+            const participant = await entityManager.getRepository(Participant)
+                .createQueryBuilder('p')
+                .select()
+                .where('p.id = :pid', { pid: engagement.participantId })
+                .andWhere('not p."dateRange" @> :edr', { edr: engagement.dateRange })
+                .getOne();
+            if (participant) {
+                throw new UserInputError('Participant ist not active in the specified dateRange');
+            }
             inserts = await entityManager.getRepository(Engagement)
                 .createQueryBuilder('engagement')
                 .insert()
@@ -280,6 +303,20 @@ export class ParticipantAPI extends DataSource {
             if (overlapping.length > 0) {
                 throw new UserInputError('Engagements with ids: ' + overlapping.map((e) => { return e.id + ', '; }) + 'are overlapping');
             }
+            // check if participant is active
+            if (engagement.dateRange && engagement.participantId) {
+                const participant = await entityManager.getRepository(Participant)
+                    .createQueryBuilder('p')
+                    .select()
+                    .where('p.id = :pid', { pid: engagement.participantId })
+                    .andWhere('not p."dateRange" @> :edr', { edr: engagement.dateRange })
+                    .getOne();
+                if (participant) {
+                    throw new UserInputError('Participant ist not active in the specified dateRange');
+                }
+            } else if (engagement.dateRange || engagement.dateRange) {
+                throw new UserInputError('Please specify participantId adn the dateRange');
+            }
             await entityManager.getRepository(Engagement)
                 .createQueryBuilder('engagement')
                 .update()
diff --git a/src/model/LendingStation.ts b/src/model/LendingStation.ts
index 9c266de..9df1441 100644
--- a/src/model/LendingStation.ts
+++ b/src/model/LendingStation.ts
@@ -34,6 +34,12 @@ export class LoanPeriod {
     })
     from: Date;
 
+    @Column({
+        nullable: true,
+        type: 'text'
+    })
+    generalRemark: string;
+
     /**
      * validity for loanPeriods
      */
diff --git a/src/model/Participant.ts b/src/model/Participant.ts
index dedf9b8..d623143 100644
--- a/src/model/Participant.ts
+++ b/src/model/Participant.ts
@@ -29,16 +29,9 @@ export class Participant implements Lockable {
     id: number;
 
     @Column({
-        type: 'date',
-        default: () => 'CURRENT_DATE'
+        type: 'daterange'
     })
-    start: Date;
-
-    @Column({
-        type: 'date',
-        nullable: true
-    })
-    end: Date;
+    dateRange: Date[];
 
     @OneToOne(type => ContactInformation, contactInformation => contactInformation.participantId, {
         nullable: false
diff --git a/src/schema/type-defs.ts b/src/schema/type-defs.ts
index cbb0e5b..b55e6a8 100644
--- a/src/schema/type-defs.ts
+++ b/src/schema/type-defs.ts
@@ -40,7 +40,7 @@ export default gql`
     type CargoBike {
         id: ID!
         "see column A in info tabelle"
-        group: Group
+        group: Group!
         name: String!
         state: BikeState
         modelName: String
@@ -410,8 +410,7 @@ export default gql`
     """
     type Participant {
         id: ID!
-        start: Date!
-        end: Date
+        dateRange: DateRange!
         contactInformation: ContactInformation!
         usernamefLotte: String
         usernameSlack: String
@@ -436,8 +435,7 @@ export default gql`
 
     input ParticipantCreateInput {
         "if not set, CURRENT_DATE will be used"
-        start: Date
-        end: Date
+        dateRange: DateRangeInput!
         "must create contactinformation first, if you want to use new"
         contactInformationId: ID!
         usernamefLotte: String
@@ -452,9 +450,7 @@ export default gql`
 
     input ParticipantUpdateInput {
         id: ID!
-        "if not set, CURRENT_DATE will be used"
-        start: Date
-        end: Date
+        dateRange: DateRangeInput
         "must create contactinformation first, if you want to use new"
         contactInformationId: ID
         usernamefLotte: String
@@ -564,7 +560,7 @@ export default gql`
 
     input EngagementCreateInput {
         engagementTypeId: ID!
-        dateRange: DateRangeInput
+        dateRange: DateRangeInput!
         participantId: ID!
         cargoBikeId: ID!
     }