# Lucene 10.0.0 backward-codecs API

Codecs for reading indexes from older versions of Lucene.
Packages
Package
Description
org.apache.lucene.backward_codecs
Common APIs for use by backwards compatibility codecs.
org.apache.lucene.backward_codecs.compressing
Compressing helper classes.
org.apache.lucene.backward_codecs.lucene40.blocktree
BlockTree terms dictionary.
org.apache.lucene.backward_codecs.lucene50
Lucene 5.0 file format.
org.apache.lucene.backward_codecs.lucene50.compressing
Lucene 5.0 compressing format.
org.apache.lucene.backward_codecs.lucene60
Lucene 6.0 file format.
org.apache.lucene.backward_codecs.lucene70
Components from the Lucene 7.0 index format.
org.apache.lucene.backward_codecs.lucene80
Components from the Lucene 8.0 index format.
org.apache.lucene.backward_codecs.lucene84
Lucene 8.4 file format.
org.apache.lucene.backward_codecs.lucene86
Lucene 8.6 file format.
org.apache.lucene.backward_codecs.lucene87
Lucene 8.7 file format.
org.apache.lucene.backward_codecs.lucene90
Lucene 9.0 file format.
org.apache.lucene.backward_codecs.lucene91
Lucene 9.1 file format.
org.apache.lucene.backward_codecs.lucene912
Lucene 9.12 file format.
org.apache.lucene.backward_codecs.lucene92
Lucene 9.2 file format.
org.apache.lucene.backward_codecs.lucene94
Lucene 9.4 file format.
org.apache.lucene.backward_codecs.lucene95
Lucene 9.5 file format.
org.apache.lucene.backward_codecs.lucene99
Lucene 9.9 file format.
org.apache.lucene.backward_codecs.packed
Legacy PackedInts methods
org.apache.lucene.backward_codecs.store
store helper