diff --git a/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/Descriptor.kt b/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/Descriptor.kt
index 21276392..73a953cb 100644
--- a/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/Descriptor.kt
+++ b/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/Descriptor.kt
@@ -18,16 +18,15 @@ typealias DescriptorId = UUID
  */
 interface Descriptor : Persistable {
     /** The [DescriptorId] held by this [Descriptor]. */
-    val id: DescriptorId
+    var id: DescriptorId
 
     /** The [RetrievableId] of the [Retrievable] that is being described by this [Descriptor]. */
-    val retrievableId: RetrievableId?
+    var retrievableId: RetrievableId?
 
     /** The [Schema.Field] backing this [Descriptor]. */
     val field: Schema.Field<*, out Descriptor>?
 
-
-    /** */
+    /** Flag indicating whether this [Descriptor] is persistent or not. */
     override val transient: Boolean
         get() = this.field != null
 
diff --git a/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/scalar/BooleanDescriptor.kt b/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/scalar/BooleanDescriptor.kt
index e0da1bca..e1334a2a 100644
--- a/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/scalar/BooleanDescriptor.kt
+++ b/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/scalar/BooleanDescriptor.kt
@@ -15,8 +15,8 @@ import org.vitrivr.engine.core.model.types.Value
  */
 
 data class BooleanDescriptor(
-    override val id: DescriptorId,
-    override val retrievableId: RetrievableId,
+    override var id: DescriptorId,
+    override var retrievableId: RetrievableId?,
     override val value: Value.Boolean,
     override val field: Schema.Field<*, BooleanDescriptor>? = null
 ) : ScalarDescriptor<Value.Boolean> {
diff --git a/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/scalar/DoubleDescriptor.kt b/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/scalar/DoubleDescriptor.kt
index c727a402..8cb8e234 100644
--- a/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/scalar/DoubleDescriptor.kt
+++ b/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/scalar/DoubleDescriptor.kt
@@ -15,8 +15,8 @@ import org.vitrivr.engine.core.model.types.Value
  */
 
 data class DoubleDescriptor(
-    override val id: DescriptorId,
-    override val retrievableId: RetrievableId,
+    override var id: DescriptorId,
+    override var retrievableId: RetrievableId?,
     override val value: Value.Double,
     override val field: Schema.Field<*, DoubleDescriptor>? = null
 ) : ScalarDescriptor<Value.Double> {
diff --git a/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/scalar/FloatDescriptor.kt b/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/scalar/FloatDescriptor.kt
index 58988a27..f0f0bf7f 100644
--- a/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/scalar/FloatDescriptor.kt
+++ b/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/scalar/FloatDescriptor.kt
@@ -15,8 +15,8 @@ import org.vitrivr.engine.core.model.types.Value
  */
 
 data class FloatDescriptor(
-    override val id: DescriptorId,
-    override val retrievableId: RetrievableId,
+    override var id: DescriptorId,
+    override var retrievableId: RetrievableId?,
     override val value: Value.Float,
     override val field: Schema.Field<*, FloatDescriptor>? = null
 ) : ScalarDescriptor<Value.Float> {
diff --git a/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/scalar/IntDescriptor.kt b/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/scalar/IntDescriptor.kt
index 2f7d924d..cbfb3ba8 100644
--- a/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/scalar/IntDescriptor.kt
+++ b/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/scalar/IntDescriptor.kt
@@ -15,8 +15,8 @@ import org.vitrivr.engine.core.model.types.Value
  */
 
 data class IntDescriptor(
-    override val id: DescriptorId,
-    override val retrievableId: RetrievableId,
+    override var id: DescriptorId,
+    override var retrievableId: RetrievableId?,
     override val value: Value.Int,
     override val field: Schema.Field<*, IntDescriptor>? = null
 ) : ScalarDescriptor<Value.Int> {
diff --git a/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/scalar/LongDescriptor.kt b/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/scalar/LongDescriptor.kt
index 45fc98b9..a9a56df2 100644
--- a/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/scalar/LongDescriptor.kt
+++ b/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/scalar/LongDescriptor.kt
@@ -15,8 +15,8 @@ import org.vitrivr.engine.core.model.types.Value
  */
 
 data class LongDescriptor(
-    override val id: DescriptorId,
-    override val retrievableId: RetrievableId,
+    override var id: DescriptorId,
+    override var retrievableId: RetrievableId?,
     override val value: Value.Long,
     override val field: Schema.Field<*, LongDescriptor>? = null
 ) : ScalarDescriptor<Value.Long> {
diff --git a/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/scalar/StringDescriptor.kt b/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/scalar/StringDescriptor.kt
index 5567053a..e6615886 100644
--- a/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/scalar/StringDescriptor.kt
+++ b/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/scalar/StringDescriptor.kt
@@ -15,8 +15,8 @@ import org.vitrivr.engine.core.model.types.Value
  */
 
 data class StringDescriptor(
-    override val id: DescriptorId,
-    override val retrievableId: RetrievableId?,
+    override var id: DescriptorId,
+    override var retrievableId: RetrievableId?,
     override val value: Value.String,
     override val field: Schema.Field<*, StringDescriptor>? = null
 ) : ScalarDescriptor<Value.String> {
diff --git a/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/struct/LabelDescriptor.kt b/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/struct/LabelDescriptor.kt
index 42105200..125b5c6b 100644
--- a/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/struct/LabelDescriptor.kt
+++ b/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/struct/LabelDescriptor.kt
@@ -14,8 +14,8 @@ import org.vitrivr.engine.core.model.types.Value
  * @version 1.0.0
  */
 data class LabelDescriptor(
-    override val id: DescriptorId,
-    override val retrievableId: RetrievableId?,
+    override var id: DescriptorId,
+    override var retrievableId: RetrievableId?,
     val label: Value.String,
     val confidence: Value.Float,
     override val field: Schema.Field<*, LabelDescriptor>? = null
diff --git a/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/struct/RasterDescriptor.kt b/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/struct/RasterDescriptor.kt
index 0caea991..72b89c5a 100644
--- a/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/struct/RasterDescriptor.kt
+++ b/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/struct/RasterDescriptor.kt
@@ -8,8 +8,8 @@ import org.vitrivr.engine.core.model.types.Type
 import org.vitrivr.engine.core.model.types.Value
 
 data class RasterDescriptor(
-    override val id: DescriptorId,
-    override val retrievableId: RetrievableId,
+    override var id: DescriptorId,
+    override var retrievableId: RetrievableId?,
     val hist: List<Value.Float>,
     val raster: List<Value.Float>,
     override val field: Schema.Field<*, RasterDescriptor>? = null
diff --git a/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/struct/SkeletonDescriptor.kt b/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/struct/SkeletonDescriptor.kt
index d7b5ad81..8d3ec7d9 100644
--- a/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/struct/SkeletonDescriptor.kt
+++ b/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/struct/SkeletonDescriptor.kt
@@ -8,8 +8,8 @@ import org.vitrivr.engine.core.model.types.Type
 import org.vitrivr.engine.core.model.types.Value
 
 data class SkeletonDescriptor(
-    override val id: DescriptorId,
-    override val retrievableId: RetrievableId,
+    override var id: DescriptorId,
+    override var retrievableId: RetrievableId?,
     val person: Value.Int,
     val skeleton: List<Value.Float>,
     val weights: List<Value.Float>,
diff --git a/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/struct/metadata/MediaDimensionsDescriptor.kt b/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/struct/metadata/MediaDimensionsDescriptor.kt
index e6bac000..de28fa22 100644
--- a/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/struct/metadata/MediaDimensionsDescriptor.kt
+++ b/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/struct/metadata/MediaDimensionsDescriptor.kt
@@ -17,8 +17,8 @@ import java.util.*
  * @version 1.0.0
  */
 data class MediaDimensionsDescriptor(
-    override val id: DescriptorId,
-    override val retrievableId: RetrievableId,
+    override var id: DescriptorId,
+    override var retrievableId: RetrievableId?,
     val width: Value.Int,
     val height: Value.Int,
     override val field: Schema.Field<*, MediaDimensionsDescriptor>? = null
diff --git a/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/struct/metadata/Rectangle2DMetadataDescriptor.kt b/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/struct/metadata/Rectangle2DMetadataDescriptor.kt
index 59847c82..70c4fa32 100644
--- a/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/struct/metadata/Rectangle2DMetadataDescriptor.kt
+++ b/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/struct/metadata/Rectangle2DMetadataDescriptor.kt
@@ -16,8 +16,8 @@ import java.util.*
  * @version 1.0.0
  */
 data class Rectangle2DMetadataDescriptor(
-    override val id: DescriptorId,
-    override val retrievableId: RetrievableId,
+    override var id: DescriptorId,
+    override var retrievableId: RetrievableId?,
     val leftX: Value.Int,
     val leftY: Value.Int,
     val width: Value.Int,
diff --git a/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/struct/metadata/TemporalMetadataDescriptor.kt b/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/struct/metadata/TemporalMetadataDescriptor.kt
index f4bae67e..fd3b36f0 100644
--- a/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/struct/metadata/TemporalMetadataDescriptor.kt
+++ b/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/struct/metadata/TemporalMetadataDescriptor.kt
@@ -16,8 +16,8 @@ import java.util.*
  * @version 1.0.0
  */
 data class TemporalMetadataDescriptor(
-    override val id: DescriptorId,
-    override val retrievableId: RetrievableId, //retrievable Id must come first, due to reflection
+    override var id: DescriptorId,
+    override var retrievableId: RetrievableId?, //retrievable Id must come first, due to reflection
     val startNs: Value.Long,
     val endNs: Value.Long,
     override val field: Schema.Field<*, TemporalMetadataDescriptor>? = null
diff --git a/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/struct/metadata/source/FileSourceMetadataDescriptor.kt b/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/struct/metadata/source/FileSourceMetadataDescriptor.kt
index c4a77719..1de8e8c1 100644
--- a/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/struct/metadata/source/FileSourceMetadataDescriptor.kt
+++ b/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/struct/metadata/source/FileSourceMetadataDescriptor.kt
@@ -16,8 +16,8 @@ import java.util.*
  * @version 1.0.0
  */
 data class FileSourceMetadataDescriptor(
-    override val id: DescriptorId,
-    override val retrievableId: RetrievableId,
+    override var id: DescriptorId,
+    override var retrievableId: RetrievableId?,
     val path: Value.String,
     val size: Value.Long,
     override val field: Schema.Field<*, FileSourceMetadataDescriptor>? = null
diff --git a/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/struct/metadata/source/MapStructDescriptor.kt b/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/struct/metadata/source/MapStructDescriptor.kt
index fc0a7fa2..53e94935 100644
--- a/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/struct/metadata/source/MapStructDescriptor.kt
+++ b/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/struct/metadata/source/MapStructDescriptor.kt
@@ -10,8 +10,8 @@ import org.vitrivr.engine.core.model.types.Value
 import java.util.*
 
 data class MapStructDescriptor(
-    override val id: DescriptorId,
-    override val retrievableId: RetrievableId,
+    override var id: DescriptorId,
+    override var retrievableId: RetrievableId?,
     val columnTypes: Map<String, String>,
     val columnValues: Map<String, Any?>,
     override val transient: Boolean = false,
diff --git a/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/struct/metadata/source/VideoSourceMetadataDescriptor.kt b/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/struct/metadata/source/VideoSourceMetadataDescriptor.kt
index 19a867a3..9b226f10 100644
--- a/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/struct/metadata/source/VideoSourceMetadataDescriptor.kt
+++ b/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/struct/metadata/source/VideoSourceMetadataDescriptor.kt
@@ -16,8 +16,8 @@ import java.util.*
  * @version 1.0.0
  */
 class VideoSourceMetadataDescriptor(
-    override val id: DescriptorId,
-    override val retrievableId: RetrievableId,
+    override var id: DescriptorId,
+    override var retrievableId: RetrievableId?,
     val width: Value.Int,
     val height: Value.Int,
     val fps: Value.Double,
diff --git a/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/vector/BooleanVectorDescriptor.kt b/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/vector/BooleanVectorDescriptor.kt
index 07077435..d5dcc468 100644
--- a/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/vector/BooleanVectorDescriptor.kt
+++ b/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/vector/BooleanVectorDescriptor.kt
@@ -16,8 +16,8 @@ import java.util.*
  */
 
 data class BooleanVectorDescriptor(
-    override val id: UUID = UUID.randomUUID(),
-    override val retrievableId: RetrievableId? = null,
+    override var id: UUID = UUID.randomUUID(),
+    override var retrievableId: RetrievableId? = null,
     override val vector: List<Value.Boolean>,
     override val field: Schema.Field<*, BooleanVectorDescriptor>? = null
 ) : VectorDescriptor<Value.Boolean> {
diff --git a/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/vector/DoubleVectorDescriptor.kt b/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/vector/DoubleVectorDescriptor.kt
index b2d2e227..46ec0081 100644
--- a/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/vector/DoubleVectorDescriptor.kt
+++ b/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/vector/DoubleVectorDescriptor.kt
@@ -16,8 +16,8 @@ import java.util.*
  */
 
 data class DoubleVectorDescriptor(
-    override val id: UUID = UUID.randomUUID(),
-    override val retrievableId: RetrievableId? = null,
+    override var id: UUID = UUID.randomUUID(),
+    override var retrievableId: RetrievableId? = null,
     override val vector: List<Value.Double>,
     override val field: Schema.Field<*, DoubleVectorDescriptor>? = null
 ) : VectorDescriptor<Value.Double> {
diff --git a/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/vector/FloatVectorDescriptor.kt b/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/vector/FloatVectorDescriptor.kt
index 4c259e9f..6e9f4ace 100644
--- a/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/vector/FloatVectorDescriptor.kt
+++ b/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/vector/FloatVectorDescriptor.kt
@@ -17,8 +17,8 @@ import java.util.*
  */
 
 data class FloatVectorDescriptor(
-    override val id: UUID = UUID.randomUUID(),
-    override val retrievableId: RetrievableId? = null,
+    override var id: UUID = UUID.randomUUID(),
+    override var retrievableId: RetrievableId? = null,
     override val vector: List<Value.Float>,
     override val field: Schema.Field<*, FloatVectorDescriptor>? = null
 ) : VectorDescriptor<Value.Float> {
diff --git a/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/vector/IntVectorDescriptor.kt b/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/vector/IntVectorDescriptor.kt
index 03ba72c9..4b3b42ee 100644
--- a/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/vector/IntVectorDescriptor.kt
+++ b/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/vector/IntVectorDescriptor.kt
@@ -16,8 +16,8 @@ import java.util.*
  */
 
 data class IntVectorDescriptor(
-    override val id: UUID = UUID.randomUUID(),
-    override val retrievableId: RetrievableId? = null,
+    override var id: UUID = UUID.randomUUID(),
+    override var retrievableId: RetrievableId? = null,
     override val vector: List<Value.Int>,
     override val field: Schema.Field<*, IntVectorDescriptor>? = null
 ) : VectorDescriptor<Value.Int> {
diff --git a/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/vector/LongVectorDescriptor.kt b/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/vector/LongVectorDescriptor.kt
index 40c3c15e..74d41884 100644
--- a/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/vector/LongVectorDescriptor.kt
+++ b/vitrivr-engine-core/src/main/kotlin/org/vitrivr/engine/core/model/descriptor/vector/LongVectorDescriptor.kt
@@ -16,8 +16,8 @@ import java.util.*
  */
 
 data class LongVectorDescriptor(
-    override val id: UUID = UUID.randomUUID(),
-    override val retrievableId: RetrievableId? = null,
+    override var id: UUID = UUID.randomUUID(),
+    override var retrievableId: RetrievableId? = null,
     override val vector: List<Value.Long>,
     override val field: Schema.Field<*, LongVectorDescriptor>? = null
 ) : VectorDescriptor<Value.Long> {
diff --git a/vitrivr-engine-module-fes/src/main/kotlin/org/vitrivr/engine/base/features/external/implementations/ASR.kt b/vitrivr-engine-module-fes/src/main/kotlin/org/vitrivr/engine/base/features/external/implementations/ASR.kt
index 2bc87c68..7906e089 100644
--- a/vitrivr-engine-module-fes/src/main/kotlin/org/vitrivr/engine/base/features/external/implementations/ASR.kt
+++ b/vitrivr-engine-module-fes/src/main/kotlin/org/vitrivr/engine/base/features/external/implementations/ASR.kt
@@ -3,7 +3,6 @@ package org.vitrivr.engine.base.features.external.implementations
 import org.vitrivr.engine.base.features.external.common.ApiWrapper
 import org.vitrivr.engine.base.features.external.common.ExternalFesAnalyser
 import org.vitrivr.engine.base.features.external.common.FesExtractor
-import org.vitrivr.engine.base.features.fulltext.FulltextRetriever
 import org.vitrivr.engine.core.context.IndexContext
 import org.vitrivr.engine.core.context.QueryContext
 import org.vitrivr.engine.core.model.content.Content
@@ -16,11 +15,15 @@ import org.vitrivr.engine.core.model.query.fulltext.SimpleFulltextQuery
 import org.vitrivr.engine.core.model.retrievable.Retrievable
 import org.vitrivr.engine.core.model.retrievable.RetrievableId
 import org.vitrivr.engine.core.model.types.Value
-import org.vitrivr.engine.core.model.types.Value.String as StringValue
 import org.vitrivr.engine.core.operators.Operator
 import org.vitrivr.engine.core.operators.ingest.Extractor
 import org.vitrivr.engine.core.operators.retrieve.Retriever
+import org.vitrivr.engine.module.features.feature.fulltext.FulltextRetriever
 import java.util.*
+import kotlin.IllegalArgumentException
+import kotlin.String
+import kotlin.require
+import org.vitrivr.engine.core.model.types.Value.String as StringValue
 
 /**
  * Implementation of the [ASR] [ExternalFesAnalyser] that uses an external FES API to analyse audio content.
diff --git a/vitrivr-engine-module-fes/src/main/kotlin/org/vitrivr/engine/base/features/external/implementations/DenseEmbedding.kt b/vitrivr-engine-module-fes/src/main/kotlin/org/vitrivr/engine/base/features/external/implementations/DenseEmbedding.kt
index ade38d50..d510689f 100644
--- a/vitrivr-engine-module-fes/src/main/kotlin/org/vitrivr/engine/base/features/external/implementations/DenseEmbedding.kt
+++ b/vitrivr-engine-module-fes/src/main/kotlin/org/vitrivr/engine/base/features/external/implementations/DenseEmbedding.kt
@@ -1,7 +1,6 @@
 package org.vitrivr.engine.base.features.external.implementations
 
 import org.vitrivr.engine.base.features.external.common.ApiWrapper
-import org.vitrivr.engine.base.features.external.common.DenseRetriever
 import org.vitrivr.engine.base.features.external.common.ExternalFesAnalyser
 import org.vitrivr.engine.base.features.external.common.FesExtractor
 import org.vitrivr.engine.core.context.IndexContext
@@ -19,6 +18,7 @@ import org.vitrivr.engine.core.model.types.Value
 import org.vitrivr.engine.core.operators.Operator
 import org.vitrivr.engine.core.operators.ingest.Extractor
 import org.vitrivr.engine.core.operators.retrieve.Retriever
+import org.vitrivr.engine.module.features.feature.external.common.DenseRetriever
 import java.util.*
 
 /**
diff --git a/vitrivr-engine-module-fes/src/main/kotlin/org/vitrivr/engine/base/features/external/implementations/ImageCaption.kt b/vitrivr-engine-module-fes/src/main/kotlin/org/vitrivr/engine/base/features/external/implementations/ImageCaption.kt
index 708b4c4a..c61a63d4 100644
--- a/vitrivr-engine-module-fes/src/main/kotlin/org/vitrivr/engine/base/features/external/implementations/ImageCaption.kt
+++ b/vitrivr-engine-module-fes/src/main/kotlin/org/vitrivr/engine/base/features/external/implementations/ImageCaption.kt
@@ -3,7 +3,6 @@ package org.vitrivr.engine.base.features.external.implementations
 import org.vitrivr.engine.base.features.external.common.ApiWrapper
 import org.vitrivr.engine.base.features.external.common.ExternalFesAnalyser
 import org.vitrivr.engine.base.features.external.common.FesExtractor
-import org.vitrivr.engine.base.features.fulltext.FulltextRetriever
 import org.vitrivr.engine.core.context.IndexContext
 import org.vitrivr.engine.core.context.QueryContext
 import org.vitrivr.engine.core.model.content.element.ImageContent
@@ -18,6 +17,7 @@ import org.vitrivr.engine.core.model.types.Value
 import org.vitrivr.engine.core.operators.Operator
 import org.vitrivr.engine.core.operators.ingest.Extractor
 import org.vitrivr.engine.core.operators.retrieve.Retriever
+import org.vitrivr.engine.module.features.feature.fulltext.FulltextRetriever
 import java.util.*
 
 
diff --git a/vitrivr-engine-module-fes/src/main/kotlin/org/vitrivr/engine/base/features/external/implementations/OCR.kt b/vitrivr-engine-module-fes/src/main/kotlin/org/vitrivr/engine/base/features/external/implementations/OCR.kt
index 238dbe90..22ff2219 100644
--- a/vitrivr-engine-module-fes/src/main/kotlin/org/vitrivr/engine/base/features/external/implementations/OCR.kt
+++ b/vitrivr-engine-module-fes/src/main/kotlin/org/vitrivr/engine/base/features/external/implementations/OCR.kt
@@ -3,11 +3,9 @@ package org.vitrivr.engine.base.features.external.implementations
 import org.vitrivr.engine.base.features.external.common.ApiWrapper
 import org.vitrivr.engine.base.features.external.common.ExternalFesAnalyser
 import org.vitrivr.engine.base.features.external.common.FesExtractor
-import org.vitrivr.engine.base.features.fulltext.FulltextRetriever
 import org.vitrivr.engine.core.context.IndexContext
 import org.vitrivr.engine.core.context.QueryContext
 import org.vitrivr.engine.core.model.content.Content
-import org.vitrivr.engine.core.model.content.element.ContentElement
 import org.vitrivr.engine.core.model.content.element.ImageContent
 import org.vitrivr.engine.core.model.content.element.TextContent
 import org.vitrivr.engine.core.model.descriptor.scalar.StringDescriptor
@@ -20,6 +18,7 @@ import org.vitrivr.engine.core.model.types.Value
 import org.vitrivr.engine.core.operators.Operator
 import org.vitrivr.engine.core.operators.ingest.Extractor
 import org.vitrivr.engine.core.operators.retrieve.Retriever
+import org.vitrivr.engine.module.features.feature.fulltext.FulltextRetriever
 import java.util.*
 
 /**