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validation/README.md

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 # ModelCIF validation tool
 
 This is a tool to check that the formatting of ModelCIF files complies with the ModelCIF format declaration (aka "dictionary"). Upon successful validation, a ModelCIF file can be extended with the dictionary version the file was compared to (option [`--extend-validated-file`](#add-validation-dictionary-to-ModelCIF-file)). For more basic mmCIF validation, the dictionary of the underlying PDBx/mmCIF format is also available.
@@ -6,7 +8,6 @@ The easiest way to run validation is from Docker container.
 
 The tool itself is a wrapper around the [`CifCheck`](https://github.com/rcsb/cpp-dict-pack) tool by [RCSB](https://www.rcsb.org/).
 
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 ## How to run the validation tool
 
@@ -28,7 +29,7 @@ $ validate-mmcif-file model.cif
 $ 
 ```
 
-### Add validation dictionary to ModelCIF file
+### Add dictionary information used for validation to ModelCIF file
 
 Since both dictionaries, ModelCIF and PDBx/mmCIF, represent actively developed file formats, different versions exist. While extending them, quite some thinking goes into making only non-breaking changes. The idea is that a ModelCIF file formatted following dictionary 1.3, is still valid with version 1.4. But the version number also tells you which feature to expect from a ModelCIF file, so it seems like a good idea to keep the version inside the file.