Field tags provide the possibility of adding metadata to the fields in your data model. There are two different types of field tags:
System field tags
System field tags are generated automatically when the script is executed and data is loaded. Some of the tags can be manipulated in the script. System tags are always preceded by a $ sign.
Custom field tags
You can add custom tags to fields in the data load script, using the Tag statement. Custom tags may not use the same name as any system tag.
System field tags
The following system field tags are generated automatically when data is loaded.
|Tag||Description||Can be manipulated in the script|
System field that is generated by Qlik Sense during script execution.
For more information, see System fields.
|$key||Key field providing a link between two or more tables.||No|
|$keypart||The field is part of one or more synthetic keys.||No|
For more information, see Synthetic keys.
Hidden field, that is, it is not displayed in any field selection list when creating visualizations, dimensions or measures. You can still use hidden fields in expressions, but you need to type the field name.
You can use the HidePrefix and HideSuffix system variables to set which fields to hide.
|$numeric||All (non-NULL) values in the field are numeric.||Yes|
|$integer||All (non-NULL) values in the field are integers.||Yes|
|$text||No values in the field are numeric.||Yes|
|$ascii||Field values contain only standard ASCII characters.||Yes|
|$date||All (non-NULL) values in the field can be interpreted as dates (integers).||Yes|
|$timestamp||All (non-NULL) values in the field can be interpreted as time stamps.||Yes|
|$geoname||Field values contain names of geographical locations, related to a point field ($geopoint) and/or an area field ($geomultipolygon).||Yes|
|$geopoint||Field values contain geometry point data, representing points on a map in the format [longitude, latitude].||Yes|
|$geomultipolygon||Field values contain geometry polygon data, representing areas on a map.||Yes|
Derived field tags
The following tags can be used when you declare derived fields to specify how to use and display the fields on a contiguous axis in a line chart. You can manipulate the tags in the data load script.
|$axis||The $axis tag is used to specify that the field should generate a tick on the contiguous axis of the chart.|
You can specify a qualified and a simplified version of an axis label by deriving two different fields. The qualified field is displayed as label when the axis is zoomed to a deeper level, to show full context.
For example, you can generate two fields when showing data by the quarter:
A simplified field, with the $simplified tag, showing quarter, like 'Q1 and a qualified field, with the $qualified tag, showing year and quarter, like '2016-Q1'.
When the time axis is zoomed out, the axis shows labels in two levels, for year (2016) and quarter (Q1), using the simplified field. When you zoom in, the axis shows labels for quarter and month, and the qualified field (2016-Q1) is used to provide full year context for the quarter.
|$cyclic||The $cyclic tag is used for cyclic fields, for example quarter or month, with a dual data representation.|