I grant that you follow your practice consistently but given the growing adoption of DITA, it would look more professional to follow standard rules on capitalization of section headings.

For example (followed by suggested changes):

2.1.2 Basic concepts

-> Basic Concepts

2.2.3.4 Processing controlled attribute values

-> Processing Controlled Attribute Values

2.2.3.8.1 Example: How hierarchies defined in a subject scheme map affect filtering

-> Example: How Hierarchies Defined in a Subject Scheme Map Affect Filtering

The general rule being that all words are capitalized other than articles (a, an, the), the coordinating conjunctions (and, but, for, nor, or, so, and yet, prepositions and the infinitive marker to. (Harbrace 9b)

I normally would not mention this but it will improve the appearance of DITA 3.0 and should be a trivial effort for a capitalization algorithm.