-Of course, this means that you must have python (at least version 1.5)
-installed in order to use LyX 1.4.x with your old documents.
-
-lyx2lyx also has the framework in place to be able to convert documents
-to an earlier format. However, these converters have only been written
-for the conversion from 1.4.x to 1.3.x, so versions of LyX older than
-1.3.0 will NOT be able to read documents saved with LyX 1.4.x.
-The conversion from 1.4.x to 1.3.x is lossless as long as no new features
-are used. lyx2lyx tries hard to find something equivalent for new
-features such as boxes, but this is known to fail sometimes.
-LyX 1.3.7 contains an updated lyx2lyx that can read documents in 1.4.x
-format. LyX 1.4.x can also export to 1.3.x format for document transfer to
-older 1.3.x releases.
+Of course, this means that you must have python (at least version 2.3.4)
+installed in order to use LyX 1.6.x with your old documents.
+
+lyx2lyx also has the framework in place to be able to convert
+documents to an earlier format (which requires python 2.3.4 at
+least). However, these converters have only been written for the
+conversion from 1.6.x to 1.5.x, 1.4.x and 1.3.x, so versions of LyX
+older than 1.3.0 will NOT be able to read documents saved with LyX
+1.6.x. The conversion from 1.6.x to 1.5.x-1.3.x is lossless as long as
+no new features are used. lyx2lyx tries hard to find something
+equivalent for new features such as boxes, but this is known to fail
+sometimes. LyX 1.5.7 contains an updated lyx2lyx that can read
+documents in 1.6.x format.
+
+Furthermore, LyX uses a converter layout2layout.py, also written in python
+that will convert old layout files on the fly. You can also call it manually
+on your layout files if you want to convert them to 1.6.x format permanently.
+
+* Preparing for Unicode:
+
+As of version 1.5.0, LyX uses Unicode internally. This is a major change that
+affects documents and layouts likewise. We have tried to do out best to make the
+transition as smooth as possible for you. However, there are some caveats:
+
+- User layout files must be converted to UTF-8
+
+ In previous versions, layout styles were allowed to use non-ASCII names
+ using the local encodings. LyX-1.5 now assumes that all layout files are
+ UTF-8 encoded. This means that non-ASCII style names are still allowed
+ but they must be valid UTF-8 strings. One way of doing the conversion
+ is to use iconv. Using bash, the script below should work:
+
+ #! /bin/sh
+
+ cd /path/to/layouts
+ for l in *
+ do
+ cp "$l" tmp.txt
+ iconv -f latin1 -t utf8 tmp.txt -o "$l"
+ done
+ rm -f tmp.txt
+
+- Inset encodings and Conversion from earlier LyX versions
+
+ As part of the transition to unicode, lyx2lyx (the scripts used for
+ converting back and forth between different versions of the lyx
+ files) converts old .lyx files, which may use a number of different
+ encodings, to UTF-8. This conversion depends on correctly
+ identifying the language of the text. There were previously some
+ edge-cases (insets embedded in different-language text type
+ scenarios) in which the language was incorrectly identified, which
+ caused some text to appear incorrectly after having upgraded from
+ older versions. This has now been fixed. Unfortunately, however, the
+ fix cannot be applied to files which have already been converted
+ past format 249. So if you have already converted your old files
+ (using a development version or release candidate), this fix won't
+ help, unless you still have the originals lying around (and haven't
+ yet made too many changes to the newer versions ;) ).
+
+Generally, it is probably wise to keep a backup of the old version of your
+files, at least until you are sure that the upgrade went smoothly (which it
+almost always will).
+
+* Languages/encodings and insets
+
+One of the bugs fixed in LyX 1.5.0 is that previously, there were certain
+specific cases in which the LaTeX generated did not correctly reflect
+language/encoding transitions in and around insets (footnotes, LyX notes).
+After much deliberation, it was decided not to change older files such that
+they will still reflect the old LaTeX output; rather, they will now correctly
+reflect the situation as it appears in the GUI. This means, however, that if
+you mangled the text in the GUI in the older versions, in order that it
+generate the correct LaTeX output, the LaTeX will now generate the mangled
+text. If this is problematic for you, please get in touch with us on the
+developers mailing list, we do have some possible solutions for this.
+
+The effects of this will be more pronounced for RTL (Hebrew, Arabic, Farsi)
+users -- though they affect users of other languages as well.
+
+* Floatflt in 1.2.x and older