Numbering Schema Class

Each NumberingSchema controls numbering for elements. Instances of NumberingSchema are also elements.

Elements belonging to a particular schema based on a filter ScopeDefiningFilter . And are organized and numbered in sequences. A sequence is a collection of elements that share the same numbering partition as defined by their respective partition matching criteria. For a numbering sequence to exist it must contain at least one element. In other words, a sequence is established once there is at least one element of which the partitioning parameters have different values then on the other elements. If the last element is removed (deleted or if it's partitioning parameters have values corresponding to another partition) the then empty sequence ceases to exist.

Elements get assigned to sequences either upon their creation (based on the then current numbering partition criteria)

In addition to directly or indirectly changing the partitioning criteria, numbering sequences can be reorganized by using methods of the NumberingSchema class. The SetMatchingParameters method changes the parameters used to assign the same number to multiple elements in the same schema. The SetPartitioningParameters method sets the parameters used in the partitioning criteria allowing a set of elements that have the same value for this set of parameters to be numbered independently. The property MatchGeometry is used to match the elements in this schema based on their geometry. The property UseBuiltInMatching is used to match the elements based on internal logic specific for that element. All the matched or partitioned elements will be renumbered and matched as needed based on the matching algorithm.

Elements in different sequences are numbered independently, meaning that there may be elements with the same number in two sequences even though the elements are different. Likewise, there may be perfectly identical elements in two or more sequences bearing different numbers. However, within each one numbering sequence any two matched elements will always have the same number, while different elements will never have the same number within a numbering sequence. Revit refers to this rule as the matching policy.

Enumerable elements are always numbered automatically upon their creation. Each new element will get an incrementally higher number. However, thanks to the matching policy, new elements that match existing elements within the same sequence will get the same number assigned. Elements will keep their assigned numbers as long as it is possible. This means, for example, that if some previously created elements (e.g. Rebar) get deleted, all remaining elements (within the same numbering sequence) will keep their numbers, which may result in gaps in the respective numbering sequence. Gaps can be removed by invoking RemoveGaps for sequences in which gaps are not desired.

Numbers are stored as values of a numbering parameter on each numbered element. The Id of the parameter is obtained by querying the NumberingParameterId property. The value of the number can be obtained by querying for the value of the parameter for the respective numbered element. If set the system will try to maintain consistency and if the input number is in use an actionable warning will be displayed.

Even though numbers are always assigned automatically to all elements of a schema, the method ChangeNumber gives the programmer a way to explicitly overwrite a specific number as long as the new number is unique in the numbering sequence. The caller specifies a number to be changed and a new value that is to be applied, providing the value does not exist yet in the same numbering sequence. Although this operation may seem rather limited, it provides the programmer with freedom to change practically any number even if it may be achieved in multiple steps. The input for this method is not the formatted version of the number, but the integer value used in the generation of the formatted number. To obtain the non-formatted numbers see GetNumbers and GetNumberingInfoForReferences

Formatting is controlled trough the NumberingFormatSettings . To get access to this object see GetFormatting . and to set it SetFormatting . The formatting getter returns a copy of the NumberingFormatSettings, if modified, the setter must be used for the changes to be applied.

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