diff --git a/src/mol-data/int/impl/interval.ts b/src/mol-data/int/impl/interval.ts
index 79b9b12730e6e89a4e6f4392533b4d56d08888b7..540b7b38bafb8c096d241948ea96421d58b8d2a0 100644
--- a/src/mol-data/int/impl/interval.ts
+++ b/src/mol-data/int/impl/interval.ts
@@ -8,7 +8,7 @@ import Tuple from '../tuple'
 
 export const Empty = Tuple.Zero;
 export function ofRange(min: number, max: number) { return max < min ? Tuple.create(min, min) : Tuple.create(min, max + 1); }
-export function ofBounds(min: number, max: number) { return max <= min ? Tuple.create(min, min) : Tuple.create(min, max); }
+export function ofBounds(start: number, end: number) { return end <= start ? Tuple.create(start, start) : Tuple.create(start, end); }
 export const is = Tuple.is;
 
 export const start = Tuple.fst;
diff --git a/src/mol-data/int/impl/segmentation.ts b/src/mol-data/int/impl/segmentation.ts
index 7caa3bfb8919e5476fddf430ccc793f8df786fc3..fed6a7fb70a7f6e9854529323651752e5680b124 100644
--- a/src/mol-data/int/impl/segmentation.ts
+++ b/src/mol-data/int/impl/segmentation.ts
@@ -10,7 +10,14 @@ import Interval from '../interval'
 import SortedArray from '../sorted-array'
 import Segs from '../segmentation'
 
-type Segmentation = { segments: SortedArray, segmentMap: Int32Array, count: number }
+interface Segmentation {
+    /** Segments stored as a sorted array */
+    segments: SortedArray,
+    /** Mapping of values to segments */
+    segmentMap: Int32Array,
+    /** Number of segments */
+    count: number
+}
 
 export function create(values: ArrayLike<number>): Segmentation {
     const segments = SortedArray.ofSortedArray(values);
diff --git a/src/mol-data/int/interval.ts b/src/mol-data/int/interval.ts
index dc5b0de839c2eb0bbd5fe8d7f0b94a6eb27bf6e2..2b4c6cd17238ffa7f8a06574427f3b29422f3b8c 100644
--- a/src/mol-data/int/interval.ts
+++ b/src/mol-data/int/interval.ts
@@ -10,34 +10,47 @@ namespace Interval {
     export const Empty: Interval = Impl.Empty as any;
 
     export const ofSingleton: (value: number) => Interval = (v) => Impl.ofRange(v, v) as any;
-    /** Create interval [min, max] */
+    /** Create interval from range [min, max] */
     export const ofRange: (min: number, max: number) => Interval = Impl.ofRange as any;
-    /** Create interval [min, max) */
+    /** Create interval from bounds [start, end), i.e. [start, end - 1] */
     export const ofBounds: (start: number, end: number) => Interval = Impl.ofBounds as any;
     export const is: (v: any) => v is Interval = Impl.is as any;
 
+    /** Test if a value is within the bounds of the interval */
     export const has: (interval: Interval, x: number) => boolean = Impl.has as any;
     export const indexOf: (interval: Interval, x: number) => number = Impl.indexOf as any;
     export const getAt: (interval: Interval, i: number) => number = Impl.getAt as any;
 
+    /** Start value of the interval, same as min value */
     export const start: (interval: Interval) => number = Impl.start as any;
+    /** End value of the interval, same as max + 1 */
     export const end: (interval: Interval) => number = Impl.end as any;
+    /** Min value of the interval, same as start value */
     export const min: (interval: Interval) => number = Impl.min as any;
+    /** Max value of the interval, same as end - 1 */
     export const max: (interval: Interval) => number = Impl.max as any;
+    /** Number of values in the interval */
     export const size: (interval: Interval) => number = Impl.size as any;
+    /** Hash code describing the interval */
     export const hashCode: (interval: Interval) => number = Impl.hashCode as any;
 
+    /** Test if two intervals are identical */
     export const areEqual: (a: Interval, b: Interval) => boolean = Impl.areEqual as any;
+    /** Test if two intervals are intersecting, i.e. their bounds overlap */
     export const areIntersecting: (a: Interval, b: Interval) => boolean = Impl.areIntersecting as any;
+
+    /** Test if interval b is fully included in interval a */
     export const isSubInterval: (a: Interval, b: Interval) => boolean = Impl.isSubInterval as any;
 
     export const findPredecessorIndex: (interval: Interval, x: number) => number = Impl.findPredecessorIndex as any;
     export const findPredecessorIndexInInterval: (interval: Interval, x: number, bounds: Interval) => number = Impl.findPredecessorIndexInInterval as any;
     export const findRange: (interval: Interval, min: number, max: number) => Interval = Impl.findRange as any;
 
+    /** Get a new interval that is the intersection of the two intervals */
     export const intersect: (a: Interval, b: Interval) => Interval = Impl.intersect as any;
 }
 
+/** Interval describing a range [min, max] of values */
 interface Interval { '@type': 'int-interval' }
 
 export default Interval
\ No newline at end of file