diff --git a/examples/matroskachapters.dtd b/examples/matroskachapters.dtd
index ef768613e..d7673923e 100644
--- a/examples/matroskachapters.dtd
+++ b/examples/matroskachapters.dtd
@@ -1,3 +1,4 @@
+<!ENTITY % format "(ascii|base64|hex)">
 <!ELEMENT Chapters (EditionEntry*)>
 <!ELEMENT EditionEntry (
           EditionUID?,
@@ -59,13 +60,16 @@
 <!ELEMENT ChapterSkipType (#PCDATA)>
 
 <!ELEMENT ChapterSegmentUID (#PCDATA)>
+<!ATTLIST ChapterSegmentUID format %format; "ascii">
 <!ELEMENT ChapterSegmentEditionUID (#PCDATA)>
 <!ELEMENT ChapterPhysicalEquiv (#PCDATA)>
 
 <!ELEMENT ChapterProcessCodecID (#PCDATA)>
 <!ELEMENT ChapterProcessPrivate (#PCDATA)>
+<!ATTLIST ChapterProcessPrivate format %format; "ascii">
 <!ELEMENT ChapterProcessTime (#PCDATA)>
 <!ELEMENT ChapterProcessData (#PCDATA)>
+<!ATTLIST ChapterProcessData format %format; "ascii">
 
 <!ELEMENT ChapterString (#PCDATA)>
 <!ELEMENT ChapterLanguage (#PCDATA)>
diff --git a/examples/matroskasegmentinfo.dtd b/examples/matroskasegmentinfo.dtd
index 031fcfacd..e0987f33d 100644
--- a/examples/matroskasegmentinfo.dtd
+++ b/examples/matroskasegmentinfo.dtd
@@ -1,3 +1,4 @@
+<!ENTITY % format "(ascii|base64|hex)">
 <!ELEMENT Info (
           SegmentUID?,
           NextSegmentUID?,
@@ -9,9 +10,13 @@
           ChapterTranslate*)>
 
 <!ELEMENT SegmentUID (#PCDATA)>
+<!ATTLIST SegmentUID format %format; "ascii">
 <!ELEMENT NextSegmentUID (#PCDATA)>
+<!ATTLIST NextSegmentUID format %format; "ascii">
 <!ELEMENT PreviousSegmentUID (#PCDATA)>
+<!ATTLIST PreviousSegmentUID format %format; "ascii">
 <!ELEMENT SegmentFamily (#PCDATA)>
+<!ATTLIST SegmentFamily format %format; "ascii">
 <!ELEMENT SegmentFilename (#PCDATA)>
 <!ELEMENT NextSegmentFilename (#PCDATA)>
 <!ELEMENT PreviousSegmentFilename (#PCDATA)>
diff --git a/examples/matroskatags.dtd b/examples/matroskatags.dtd
index 0de53f601..014987054 100644
--- a/examples/matroskatags.dtd
+++ b/examples/matroskatags.dtd
@@ -1,3 +1,4 @@
+<!ENTITY % format "(ascii|base64|hex)">
 <!ELEMENT Tags (Tag*)>
 <!ELEMENT Tag (
           Targets,
@@ -29,5 +30,6 @@
 <!ELEMENT Name (#PCDATA)>
 <!ELEMENT String (#PCDATA)>
 <!ELEMENT Binary (#PCDATA)>
+<!ATTLIST Binary format %format; "ascii">
 <!ELEMENT TagLanguage (#PCDATA)>
 <!ELEMENT DefaultLanguage (#PCDATA)>