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###########
Input Files
###########
SCRAM uses XML input files to describe analysis.
One model per run is assumed.
See :ref:`xml_tools` for more convenient writing and reading of XML input files.
The input file format follows
the Open-PSA Model Exchange Format ([MEF]_) version 2.0d or later.
The extensive description is given in the above format documentation by Open-PSA,
and input files should be straightforward to create and understand.
However, not all Open-PSA formatting is supported,
and some additional assumptions/restrictions are made by SCRAM.
See :ref:`opsa_support` for the format description
and current implementation with differences.
In addition to the XML format,
the :ref:`Aralia_format` is supported indirectly.
Encodings
=========
- UTF-8
- UTF-16
- other encodings supported by `GNOME XML Parser`_ on the given platform.
.. _GNOME XML Parser: http://xmlsoft.org/encoding.html
Steps in XML Input Validation
=============================
#. Several input files to describe one model.
- The first file must define the name, label, and attributes of the model.
This information about models in the other input files is ignored without a warning,
which allows reuse of files with analysis constructs from other models.
#. XML input file validation against the `RELAX NG`_ :ref:`schema`.
#. The validation assumptions/requirements:
- Construct names and references are case-sensitive.
- Leading and trailing whitespace characters are trimmed.
- Names and references should conform to the MEF recommendations.
- Public names must be unique globally,
and private names must be unique locally within containers.
- References are followed according to the public and private roles
described in the Open-PSA MEF section
*IV.3.2. Solving Name Conflicts: Public versus Private Elements*.
#. Additional validation of fault trees and values of parameters:
- Each gate or formula must have the correct number of arguments.
- A duplicate argument in Boolean formulas or gates is an error.
- Values of expressions and parameters must be valid, i.e., non-negative for probabilities.
- All events must be explicitly defined for probability calculations.
#. Error messages (with a file name, line numbers, types of errors):
- Report a cyclic tree (gates or event tree branches).
- Report a cyclic parameter with expressions.
- Report a cyclic rule with instructions.
- Report missing element descriptions.
- Report an error if an event or a construct is being redefined.
#. Warnings for potential errors:
- Unused model constructs:
* Primary events
* Parameters
* Event trees
* Initiating events or event groups
* Functional events, branches, sequences, rules
* Extern functions and libraries
.. _schema:
Validation Schemas
==================
- `RELAX NG Schema <https://github.com/rakhimov/scram/blob/master/share/input.rng>`_
.. _Aralia_format:
Aralia Input Format
===================
A more convenient format than the XML for writing simple fault trees
utilizes a shorter notation for gates, operators (``&``, ``|``, ``@``, ``~``, ``^``), and events
to create a collection of Boolean formulas.
The Aralia format can be converted into the XML format with `this script`_.
.. _this script:
https://github.com/open-psa/translators/blob/master/aralia.py
Input File Examples
===================
Fault Tree Input File
---------------------
.. literalinclude:: example/input.xml
:language: xml
Aralia Version
--------------
.. literalinclude:: example/aralia_input.txt
.. _RELAX NG: http://relaxng.org/
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