Creating Datum Group

You can create a new datum group record by clicking on the Create Datum Group button when in edit mode.

You must have clicked the Start Spatial Edits button and have selected the layer to work with. Then, when the Create Datum Group button is pressed, the Create Datum Group dialog opens.

Note that each organization may define its own attributes for the datum group, so the dialog that you will work with may differ than the example shown here.

The dialog consists of 3 tabs:

General
Members
Additional Data

The General tab consists of the following fields:

Group Properties

Unique Name: Blank, or displays the Unique reference for the Group of Datum Elements. If the Network type for this group has been defined as not automatically generating the unique key, the value for the Unique field will also be displayed in the Flexible attributes panel. This field will be blank until the datum group is saved if the unique name is calculated.
Note: Care should be taken if the Unique reference of a Group is to be wholly contained within part of the Unique Element reference to ensure that the String Length specified for the attribute column, e.g. NE_GROUP, is of sufficient length to contain the Unique of the Group
Description: Enter a description for the Group. This is a mandatory field.
Start Date: Displays the date from which the Group of Elements is effective. When creating a new group this field will default to today's date. To change the date click on the down arrow and select the required date from the calendar. The Start Date is a mandatory field.
Group Type: Displays the Group type for the currently selected group. This field is read-only. When creating a new group, press the button next to the field to select a Group type. Only Group Types associated with the Network Type will be listed.
Network Type: The Network Type associated with the selected Group Type will be displayed in the 'Network Type' field. This field is read-only.
Admin Unit: Displays the Admin Unit for the Group. When creating a new group, click on the button next to the field to select the required Admin Unit for the Group. Only Admin Units of the Admin Type associated with the Network Type used when defining the Group Type of the selected Group of Elements will be displayed in the list of values. Only Users with sufficient Admin Unit privileges will be permitted to use the Group.
End Date: This field is non-updateable. To End-date (close) the group you need to use the Close button. Click here for more information on Closing a group.
Measured Length: The calculated length of the route. This field is read-only.
Length Units: The Units of Measurement associated with the Network Type which in turn is associated with the Group type selected will be displayed in the 'Length Units' field. This field is read-only.
Min and Max Offset: A route is defined by each of its member datum network elements. For example, if you have a route that is defined by 3 datums:
- Datum A: 10m
- Datum B: 15m
- Datum C: 5m
If you define your route as including the ENTIRETY of these datums, the route would have a Measured Length of 30m, a Min Offset of 0 and a Max Offset of 30, i.e. equal to the Measured Length.

But if define your route as starting 5m from the beginning of the route, the Measured Length is 25, the Min Offset is 5, and the Max Offset (which is the max length the route can take) would be 30.

Note: Group types can be defined as partial, which means that they can include just parts of member datum network elements, or not.

Once you have updated the group attributes click Save to create the group record.

Attributes

The Attributes section displays any attributes that have been defined for the Network Type the Group belongs to using the Network Types form. The attributes that are included are defined by the organization and will vary from one organization to another.

Members Tab

The Members tab lists the datum network elements that are part of the group. When the initial group record is first created you will not be able to add member records until the group is saved.

You can add one or more datum network elements to an existing group by either:

Adding Members Using the Map (only when in spatial editing mode)
Adding Members Using the Form The following information is displayed for each member Element:

Sequence Number: If the selected Group is 'Linear' and therefore member Elements are connected via shared Nodes Points or by means of Distance Breaks the Elements will be 'sequenced' to establish their relative position in the Group and hence enables displacements to be calculated.
ID: The Unique reference of the member Element.
Name
Start Node: The Start Node of the selected Network Element.
End Node: The End Node of the selected Network Element.
Start: This field displays the start position, relative to the member Element, of the extent of the Element which is contained within the Group. For non partial groups this value will always be '0'. For Partial Groups this value may be updated.
End: This field displays the end position, relative to the member Element, of the extent of the Element which is contained within the Group. For non partial groups this value will always equate to the Element length. For partial Groups this value may be updated.
Partial Indicator: If the Group is a 'Partial' Group and the selected member Element is not wholly contained with the Group, i.e. the 'Start' or/and 'End' fields have been amended, the system will automatically 'check' this partial indicator.
Membership Length: The total Length of the extent of the member Element contained within the Group.
Member Length
Offset: The offset value for the start of each member Element will be displayed. This value is the measured distance value of the start of the Element, relative to the parent Group in increasing measure from its start.
POE (Point of Equation Indicator): If a Point of Equation exists at the Start Node of an Element (the End Node if the member Element is not in the Cardinal direction of the Route) the type of POE will be indicated in Red. A POE is a discontinuity in the measured distance of a Route at a known point on the ground, i.e. a Node point, and can either be a GAP or an OVERLAP. Points of Equation may be created as a result of the Network operations needed to model a Road Realignment or as a result of a 'Shift' or 'Recalibrate' operation. Points of Equation may be removed by 'Rescaling' the Route.
Cardinality Indicator: If a member Element is in the Route Cardinal Direction, i.e. the Element is increasing in measure value from its Start Node to its End Node in the same direction as the increasing measure of the Route from its Start, this box will be checked.
Start Date: Enter the Date from which the Element is a member of the Parent Group. If the Group is a Parent in a Type Inclusion for a Datum Network the Start Date will be automatically populated as the date the Element record was created. If the Group is 'Rescaled' the Start Date will be set to the Date the Rescale operation took place.
End Date: Enter the Date from which the Element is no longer a member of the Group. If the Group is a Parent in a Type Inclusion for a Datum Network, the member Elements will be End Dated if the Parent Route is Closed using the Close Route facility.

You can perform several Actions from the Member tab. See Managing Linear Datum Groups and the subtopics for more information on these actions.

Additional Data

This tab will hold any Additional Data Type records that have been defined for the Group Type the current Group belongs to. For more information see Editing Additional Attribute Data for Network Types.