The schema of `pw.x` and `cp.x` ( actually as of today, 17 May 2019, some parts of the xml related to CP still need to be integrated on the schema) may be found in this repository in the directory `xsd/`. The files `qes_<reversedate>.xsd` are all successive versions of the schema.
The root element of the xml I/O file of for `pw.x` and `cp.x` is called espresso, the description of the content of the espresso element is given by the complex_type `espressoType`.
The espressoType is composed by many sub-elements. In order of importance.
1.`input` element containing the input for running `pw.x` or `cp.x`
2.`output` element containing all output data reporting the results of the calculation
2.`step` these are possible multiple elements in the file reporting the configuration and energetics of a trajectory for MD simulations or relaxation paths. Their number is by default 250.
3.`parallel_info` reporting the information about the parallel environment where the calculation was run
3.`timing_info` reporting the timing information
4.`general_info` reporting some general info about the version of the code and others
5.`status` reporting the exit status of the run
the only one which is mandatory is the `input` element. This is because the xml file may actually be used as the input of the calculation and all the other elements which are produced after the program has finished are obviously missing. The file printed as output also includes the starting input element plus all the other elements.
## General rules when adding elements to the schema.
## What to do if you want to add a variable to input element.
