Converting SFM Bibles to OSIS

Introduction

Standard Format Markers (SFM) and its more standardized derivative USFM have been used for decades to store Bibles for printing and display in programs like UBS Paratext. The format is popular among Bible translation agencies and Bible societies. The basic format of SFM is simply plaintext with backslash(\) codes. For example, a new Bible verse is signaled by \v followed by the number of the verse.

Older texts in various dialects of SFM can still be found. It was common for various agencies, Bible societies, and even regional offices of such groups to have their own SFM standards. Unified Standard Format Markers (USFM) was developed to standardize SFM and encourage interoperability so that Bibles from one agency could be reasonably expected to operate with the software and style sheets employed by another. USFM version 2.4 is the latest one documented.

Preparing (U)SFM files for conversion

The simplicity of writing SFM also makes it easy to write poor SFM that fails to correspond to any kind of standard. The first task in preparing to convert SFM files to OSIS is to clean the text. The more regular your source files are, the more likely the conversion process will operate correctly.

One method of cleaning up your files is to import them into an SFM editor such as Bibledit (which runs on Linux, Mac OS X, and Windows) or SIL FieldWorks Translation Editor (which runs on Windows). The editors will frequently perform some basic corrections to the SFM syntax, but Bibledit in particular can perform a number of checks to correct specific errors common to SFM.

As of March 2013, after a formal agreement was signed with UBS, anyone who is a member of CrossWire's publishing staff is allowed to register and download Paratext software - subject to individual approval by CrossWire's director. This agreement covers the software only, without giving access to the copyrighted resources associated with Paratext that are of greater use for Bible translators.

Checking USFM files for versification issues

Rather than waiting until you have the end result, a SWORD module, and then running the general utility emptyvss, it is possible to use another Windows based utility called GoBibleCreator USFM Preprocessor. Despite its name, its use is not limited to conversion of documents for use towards making Go Bible applications. Although this was originally developed for supporting the Go Bible project, it does have some useful more general features. This is one of them, and is found under the "Check for Consistency" tab. Another is the ability to export the USFM Bible into BQ/DigiStudy format. The Search for Versification Issues is particularly helpful for Bibles structured primarily as "verse per line", rather than as paragraphs containing a verse range. Another useful feature is the identification of non-standard markers.

USFM tag statistics

Before embarking on any USFM conversion to another format, it's often very useful to list all the different USFM markers (tags) that are used in the project SFM files. Osk has developed a Python script called usfmtags.py to perform this task. It can be downloaded from his GitHub repository [2].

Converting USFM files to OSIS

This section gives details of software utilities capable of converting USFM files to OSIS.

All such conversions require the use of eXtensions to OSIS of one form or another. Whether these are supported by the SWORD engine should be researched before users conclude that there are faults with the particular conversion method.

usfm2osis.py

Osk has released a new Python script to convert USFM to OSIS. Download from [3]. One of the stated aims was to achieve full coverage of USFM according to the ParateXT spec.

Notes:

1. usfm2osis.py version 0.6 is not a full production release. Refer to the roadmap within the script.
2. usfm2osis.py will always only generate best practice OSIS, to the best of its ability, so it won't generate stuff that SWORD requires due to its own shortcomings.
3. usfm2osis.py generates OSIS with the milestone form of both chapter and verse elements.
4. usfm2osis.py doesn't yet use SWORD bindings, so it's very limited in its knowledge of versification systems. This may mean that for the time being, expanding cross-references would typically have to be done by other means. See below.
5. In general, anyone interested in converting USFM to OSIS for use with SWORD ought now to employ usfm2osis.py as it's now the only supported pathway for USFM->OSIS->SWORD, inasmuch as its author has a fairly close connection with SWORD and regularly commits stuff to SWORD filters and whatnot. He will definitely not make the least effort to accommodate any non-standard output from converters other than usfm2osis.py.
6. It is advised to use Python 2.7.x rather than Python 3.x as there are still some issues in getting the script to work with Python 3.
7. Windows users are advised that should they encounter problems trying to run the script with ordinary CPython from python.org, to use the Python interpreter that can be installed with Cygwin. This would also help for specifying the input files using wildcards.
8. Useful tip: Cygwin's bash shell recognizes NTFS symbolic links. This means that the USFM input files and the Python script don't need to be copied to the cygwin/home/user directory. Just make suitable links by means of the Windows mklink command.
9. Bug reports and feature requests are welcomed at either [4] or sword-support.

Usage

usfm2osis.py requires a Python interpreter in the system path.

Optional: If you wish the script to validate the OSIS output, then you'll need to install lxml.

The usage of usfm2osis.py is output when the script is run without parameters, i.e. with the shell command line

python usfm2osis.py

The syntax is very close to that for usfm2osis.pl – see below.

XML Syntax Checking

Until the Python script is fully debugged, it's possible that it may generate an OSIS file that fails the XML syntax check. As and when this occurs, it is always useful to isolate the location[s] of the XML file where the syntax is incorrect. This can be done by making separate OSIS XML files for each USFM file, or at least to exclude suspect files from the build by temporarily renaming the file extensions such that it does not match the wildcard pattern used in the command line.

OSIS Validation

Until the Python script is fully debugged, it's quite possible that even though you have an OSIS file that passes the XML syntax check, it may still fail to validate to the OSIS schema. Similar techniques are useful here too. Make an individual OSIS file from each USFM file, so that the valid files can be distinguished from the invalid files. This facilitates further investigation to more easily locate the invalid elements.

Unsupported Markers

Please refer to the roadmap within the script itself if you encounter any unsupported USFM tags.

Note:

usfm2osis.pl

usfm2osis.pl is a simple Perl script intended only for converting USFM files to OSIS. It does not provide comprehensive cover for all the tags in the USFM Reference.

Notes:

1. usfm2osis.pl is now deprecated. Please use the Python script instead. See above.
2. Its output was geared towards the use of OSIS documents in preparing to make SWORD modules.
3. usfm2osis.pl generates OSIS with the milestone form of both chapter and verse elements.
4. usfm2osis.pl is no longer being actively maintained by CrossWire.

Usage

usfm2osis.pl requires a Perl interpreter in the system path. Then you can run:

perl usfm2osis.pl <osisWork> [-o OSIS-file] [-e USFM encoding] <USFM filenames|wildcard>

If usfm2osis.pl is not in the current directory, use its full path.

osisWork should be a value such as Bible.en.WEB.2007.

If you include an OSIS-file value, the output will be written there. Otherwise, it will be written to a file name based on your osisWork.

The USFM encoding argument should indicate the character encoding found in the source files. If none is given, UTF-8 is the default. The list of available encodings depends on your system. Executing the script with no arguments will print the list (as will executing it with an invalid encoding value).

The final argument is a list of filenames or a wildcard value such as *.sfm containing the SFM data.

Notes:

1. In Windows, a wildcard as one of the usfm2osis.pl parameters does not work. This is due to the way the Windows command shell (cmd.exe) does not expand the wildcard parameter. If you have CygWin installed, the bash shell solves this problem, because it expands the wildcard filename specifier.
2. In Windows, the following command line syntax will create an OSIS file for each SFM file. This assumes the current directory is the folder where the SFM files are stored, and that there is a same-level directory called osis. It also illustrates the use of (subsititute) drive p: for the full path to usfm2osis.pl, and omits the USFM encoding parameter merely for clarity. The additional use of %f within the output filenames is to give each OSIS XML file a unique name.

for %f in (*.SFM) do perl p:\usfm2osis.pl <osisWork> -o ..\osis\<osisWork>.%f.osis.xml %f

Similarly in CygWin or another bash environment you can use

for f in $(ls *.SFM); do perl usfm2osis.pl <osisWork> -o ../osis/<osisWork>.$f.osis.xml $f; done

Unsupported Markers

Not all USFM tags are currently supported, just those so far seen "in the wild" by the maintainers of the script. The comments of the script document the current set of tags coverage. In view of the many omissions, it is advised to use the new Python script instead.

Fixing the OSIS XML files

This section attempts to address some of the current deficiencies in SWORD, and lists tools to workaround these issues. Eventually (it is hoped) these will not be necessary, as the fixes will be implemented within usfm2osis.py during its further development, or as fixes are made to the SWORD engine and/or front-ends, as appropriate.

OSIS hacks

OSIS 2.1.1 still lacks some desirable features or improvements. While these are not yet forthcoming, sometimes it may be necessary to implement some hacks to the OSIS generated by scripted OSIS converters to workaround these "deficiencies" in the OSIS schema. You can read about OSIS change requests (or judiciously add to the page) here.

Cross-references

usfm2osis.py and usfm2osis.pl do not produce cross-references (or parallel passage headings) that work properly as links with SWORD. If your text contains such, you need xreffix.pl which sits in directory [5]. Using it requires the SWORD Perl bindings be installed and a sword-locale for the language of the module to be created.

Note:

Miscellaneous

Many texts in non-Latin scripts (and even for some Latin scripts) require batch conversion of characters and numbers. There are several scripts to assist with this, without harming the USFM or OSIS markup.

Notes:

UBS Paratext

Since version 6, UBS Paratext has a menu option to export to OSIS.

Checking | Paratext 6 Checks | Publishing | Convert USFM to OSIS (Best Practice)

See Paratext to OSIS for illustration of this menu option.

This option generates XML files with the following schema definition file referenced.

osisCore.2.0_UBS_SIL_BestPractice.xsd

UBS SIL Best Practice OSIS makes use of several XML attributes that are not used within CrossWire, and some of these are custom (i.e. x-prefix named attributes). An accessible online copy does not seem to be available. Furthermore, the only undated copy of this .xsd file (40KB) that has been obtained includes the following lines:

   <!--    WARNING   WARNING   WARNING
  THIS SCHEMA IS DEVELOPMENTAL AND SHOULD BE USED WITH THAT UNDERSTANDING -->

Contrast the above with the standard definition file (92KB) used by CrossWire.

http://www.bibletechnologies.net/osisCore.2.1.1.xsd

Notwithstanding the above concerns, based on one sample exported from a Paratext project, it has been verified that replacing line 2 by the similar line output from usfm2osis.pl, such a converted XML file can be validated against the standard definition file.

Nevertheless, further testing (using osis2mod) of some OSIS files exported from Paratext revealed that they generated WARNING(NESTING) errors. Some of these were due to the eID milestone for a verse occurring BEFORE the sID milestone for the same verse! Others were due to </note> being placed AFTER the eID milestone for the verse where the note occurs.

Hence I conclude that what Paratext outputs as OSIS is not really "best practice", and would require some improvements to fix issues such as these. However, we know that work on OSIS export from Paratext has virtually stopped - so this may now prove to be of mere historical interest.

The bottom line is that the OSIS export from Paratext is not ready for publishing a SWORD module.

Other osis-converters

osis-converters is the location for the open source (U)SFM-to-OSIS and OSIS-to-SWORD module converters developed independently by the main programmer of xulsword.

Notes:

Creation of publication ready modules from USFM and submission to CrossWire

Checking and validating OSIS files

When checking OSIS XML files there are 3 steps:

1. Is the OSIS well formed XML ?
2. Is the file valid to the defined OSIS schema?
3. Is the file "fit for purpose" (i.e. suitable for immediate use by the SWORD conversion tool called osis2mod)

Step #1 does not guarantee step #2 and step #2 does not guarantee step #3. See above and below and limitations of XML validators.

Before you convert your OSIS files to SWORD format, you should always check that it is valid OSIS.
Before you submit any files to modules@crosswire.org, you must ensure that your files are valid OSIS. Invalid OSIS files will not be accepted.

Note:

Module creation process

This section requires updating to reflect the move to using the Python script usfm2osis.py in preference to its Perl predecessor.

Our process to create publication ready modules from USFM looks like this:

Stage 1

The command line examples in this section are for Unix. In Windows, it's not as simple to make equivalent command lines for Perl, especially in regard to globbing wildcards for filenames.

• Iterate usfm2osis.pl over each single USFM file to produce a OSIS file per USFM file

for biblebook in 'ls *usfm'; do usfm2osis.pl $biblebook $biblebook; done

• Check each OSIS file for XML validity - this will throw up a lot of not obvious USFM encoding problems

for biblebook in 'ls *osis.xml'; do checkbible $biblebook; done

• Correct USFM files as per mistakes found

Rerun this stage until you have clean and validating OSIS files.

Stage 2

1. Check the OSIS files for not transformed USFM markers.
2. Fix usfm2osis.pl and add the missing tags for correct OSIS transformation.
3. Rerun above until you have a clean validating collection of OSIS files with no left over USFM tags.
4. Send the updates to usfm2osis.pl to CrossWire's SVN repository.
5. Run usfm2osis.pl over all the USFM files and create a single large OSIS file.
6. Check again for XML validity.
7. Run the OSIS file through osis2mod, create a conf file, and check the resultant module for problems in a variety of front-ends.
8. Create a sword locale file and store in your /usr/share/sword/locales.d/ directory
9. If cross references are part of the USFM files fix these with the help of xreffix.pl (also in sword-tools).
10. Run again through osis2mod and check again.
11. Submit the final OSIS file and the conf file to CrossWire together with the locale file.
12. Send any corrections on the USFM files back to the translation team. Chances are these are all valid and necessary corrections which help to improve the USFM.

Notes: