This International Standard is applicable to all types of libraries in all countries. However, not all performanceindicators apply to all libraries. Limitations on the applicability of individual performanceindicators are listed in the scope clause of the description of each indicator (see Annex B).

Performance indicators can be used for comparison over time within the same library. Comparisons between libraries can also be made, but only with caution. Comparisons between libraries will need to take into account any differences in the constituencies of the libraries and library attributes, with a good understanding of the indicators used, limitations to comparisons, and careful interpretation of the data.

There are other limitations to the performanceindicators in this International Standard that depend on local factors, such as the community the library serves, service mandates, and technology infrastructure configuration. Results from the use of performanceindicators in this International Standard are intended to be interpreted with regard to these factors.

Performance indicators are not specified for all services, activities, and uses of the resources of the library, either because such indicators have not been proposed and tested at the time of formulation of this International Standard, or because they did not fulfil the criteria specified (see 4.2).

The performanceindicators included in this International Standard do not reflect all possible measures or evaluation techniques. This International Standard offers accepted, tested, and publicly accessible (i.e. non-proprietary) methodologies and approaches to measuring a range of library service performance.

This International Standard is not intended to exclude the use of performanceindicators not specified in it.

This International Standard does not include indicators for assessing the impact of library services either on individuals, the communities that libraries serve, or on society at this time. Library impact assessment will be dealt with by a specific International Standard (ISO 16439).

Throughout the text, the names of indicators are printed with initial capitals for significant words, e.g. LibraryVisits per Capita. This helps to distinguish the names from supporting text.