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-rw-r--r--lib/asn1/doc/src/asn1_ug.xml17
1 files changed, 17 insertions, 0 deletions
diff --git a/lib/asn1/doc/src/asn1_ug.xml b/lib/asn1/doc/src/asn1_ug.xml
index ee54fdffd7..cef7945226 100644
--- a/lib/asn1/doc/src/asn1_ug.xml
+++ b/lib/asn1/doc/src/asn1_ug.xml
@@ -1438,6 +1438,23 @@ StartMessage ::= SEQUENCE {
<c><![CDATA[&amp;Message]]></c> in the class. The <c>msgId</c> field is always
encoded as a PrintableString, since the field refers to a fixed type
in the class.</p>
+ <p>In practice, object sets are usually declared to be extensible so
+ so that more objects can be added to the set later. Extensibility is
+ indicated like this:</p>
+ <pre>
+GENERAL-PROCEDURES GENERAL-PROCEDURE ::= {
+ object1 | object2, ...} </pre>
+ <p>When decoding a type that uses an extensible set constraint,
+ there is always the possibility that the value in the UNIQUE
+ field is unknown (i.e. the type has been encoded with a later
+ version of the ASN.1 specification). When that happens, the
+ unencoded data will be returned wrapped in a tuple like this:</p>
+
+ <pre>
+{asn1_OPENTYPE,Binary}</pre>
+ <p>where <c>Binary</c> is an Erlang binary that contains the encoded
+ data. (If the option <c>legacy_erlang_types</c> has been given,
+ just the binary will be returned.)</p>
</section>
<section>