Non-sequential procedural steps
Some procedures are not made up of sequential procedural steps. When documenting these procedures, the steps-informal structure or the steps-unordered structure should be used.
Until DITA 1.2, the base content model only offered steps as a semantic structure for procedures, processes and instructions. In many ways, this one-size-fits-all approach was very limiting. A substeps element provided some scope for more complex procedures, but some believed that an upper level process element was required.
DITA 1.2 introduced the steps-informal and the steps-unordered alternatives to steps. The steps-informal structure in only available in the general task information type, while steps-unordered can be used in the (strict) task and the general task information types. One of the reasons for the introduction of the new types of steps was to provide for processes.
The steps-informal structure should be used for documenting processes where there are no distinct steps or stages.
The steps-unordered structure should be used when there are distinct steps in the procedure or process, but the order in which they are performed is not important. In other words, use steps-unordered in the same way that you might use an unordered list (ul) in a concept topic.
Do not use steps-informal or steps-unordered as a lazy way of writing unstructured steps (that is, steps without the cmd/stepresult/info vocabulary).
If you feel you need non-sequential substeps in a step element, use the choicetable structure rather than steps-informal. There is no substeps-informal structure.