It is not uncommon for the term “horizontal standard” to surface. This involves broad-spectrum standards of general character. Their intent is to standardize basic principles, concepts or terminology. An important characteristic of horizontal standards is that they must be referenced in all new or revised product standards. This means these are established high in the hierarchy. If they additionally involve a harmonized standard (EN), these will also be found in CE certificates. An example of a horizontal standard is IEC 82079-1 “Preparation of instructions for use”.
In various industry sectors, the basic standards can be seen as belonging to the horizontal standards. Thus, in the vertical standards, there are also generic standards and product standards.
Individual product standards may only contain additions to a horizontal standard; they describe special requirements for procedures, products or product groups.
The hierarchy is very clear in the mechanical engineering field. Here, the hierarchy is classified into Type A (basic safety standard), Type B (generic safety standard), Type B1, Type B2 and Type C standards (generic standard). Type A is the horizontal basic safety standard (EN ISO 12100) and Type B a standard dealing with a specific aspect. Type B can exist in the form B1 (safety aspects, e.g. EN 1037) or B2 (protective equipment, e.g. EN 1088). Type C is lower in the hierarchy, i.e. even more specific, and regulates detailed safety requirements (e.g. EN 12717 “Safety of machine tools - Drilling machines”). What is particular about Type C is that it has priority if it substantiates, or deviates from, one or more specifications in Type A or Type B. Type C can thus be, under certain circumstances, high in the hierarchy (less specific) and therefore advantageous to manufacturers.