diff --git a/README.md b/README.md
index ac0d6aa..d24e20d 100644
--- a/README.md
+++ b/README.md
@@ -53,6 +53,9 @@ The fragment ID is parsed from the file name:
 - `BM <number>.csv` => `BM.<number without leading zeroes>`
 - `AA-BB-CC 0DD.csv.csv` => `18AA,<BB padded to to digits><CC padded to two digits>.<DD without leading zeroes>`
 - `AA-BB-CC,DD.csv` => `18AA,<BB padded to to digits><CC padded to two digits>.<DD without leading zeroes>`
+- `CBS <id>.csv` => `CBS.<id>`
+- `N <id>.csv` => `N.<id>`
+- `UM <id>.csv` => `UM.<id>`
 
 References from different files resulting in same fragment ID are combined for the final result.
 
diff --git a/lib/mapNames.js b/lib/mapNames.js
index 185d5c4..13b0e5d 100644
--- a/lib/mapNames.js
+++ b/lib/mapNames.js
@@ -1,5 +1,22 @@
 const _ = require('lodash')
 
+class IdMapper {
+  constructor (pattern, factory) {
+    this.pattern = pattern
+    this.factory = factory
+    this.match = null
+  }
+
+  createMatch (fileName) {
+    this.match = this.pattern.exec(fileName)
+    return this.getId()
+  }
+
+  getId () {
+    return this.match && this.factory(this.match)
+  }
+}
+
 function parseCollection (collection) {
   return collection
     ? ['Rm 2', 'Rm II'].includes(collection)
@@ -14,6 +31,12 @@ function createCollectionName (match) {
   return `${collection}.${number}`
 }
 
+function createPennMuseumName (match) {
+  const collection = parseCollection(match.groups.collection)
+  const number = match.groups.number
+  return `${collection}.${number}`
+}
+
 function createDateName (match) {
   const year = `18${match.groups.year}`
   const month = match.groups.month.padStart(2, '0')
@@ -23,16 +46,20 @@ function createDateName (match) {
 }
 
 module.exports = function mapName (fileName) {
-  const collectionPattern = /^(?:(?<collection>Sm|DT|Rm|Rm 2|Rm II|BM|CBS|N|UM) )?(?<number>\d+)\.csv$/
-  const collectionMatch = collectionPattern.exec(fileName)
-  const datePattern = /^(?<year>\d{2})-(?<month>\d{1,2})-(?<day>\d{1,2})[ ,](?<number>\d+)\.csv$/
-  const dateMatch = datePattern.exec(fileName)
-
-  if (collectionMatch) {
-    return createCollectionName(collectionMatch)
-  } else if (dateMatch) {
-    return createDateName(dateMatch)
-  } else {
-    return null
-  }
+  const id = [
+    new IdMapper(
+      /^(?:(?<collection>Sm|DT|Rm|Rm 2|Rm II|BM|CBS|N|UM) )?(?<number>\d+)\.csv$/,
+      createCollectionName
+    ),
+    new IdMapper(
+      /^(?<collection>CBS|N|UM) (?<number>.+)\.csv$/,
+      createPennMuseumName
+    ),
+    new IdMapper(
+      /^(?<year>\d{2})-(?<month>\d{1,2})-(?<day>\d{1,2})[ ,](?<number>\d+)\.csv$/,
+      createDateName
+    )
+  ].map(mapper => mapper.createMatch(fileName)).find(_.negate(_.isNil))
+
+  return id || null
 }
diff --git a/lib/mapNames.test.js b/lib/mapNames.test.js
index 11207ca..501e8a5 100644
--- a/lib/mapNames.test.js
+++ b/lib/mapNames.test.js
@@ -15,9 +15,9 @@ test.each`
   ${'63-2-9,123.csv'}   | ${'1863,0209.123'}
   ${'BM 12345.csv'}     | ${'BM.12345'}
   ${'BM 123456.csv'}    | ${'BM.123456'}
-  ${'CBS 123456.csv'}   | ${'CBS.123456'}
-  ${'N 123456.csv'}     | ${'N.123456'}
-  ${'UM 123456.csv'}    | ${'UM.123456'}
+  ${'CBS 587bis.csv'}   | ${'CBS.587bis'}
+  ${'N 708A.csv'}       | ${'N.708A'}
+  ${'UM 29-16-055.csv'} | ${'UM.29-16-055'}
   ${'invalid.xlsx'}     | ${null}
 `('returns $fragmentId for $fileName', ({ fileName, fragmentId }) => {
   expect(mapNames(fileName)).toBe(fragmentId)