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The Quick filters button has a selection of pre-configured JQL-based filters. See the https://stagil.atlassian.net/wiki/spaces/SIMFJ/pages/2171830294/Administration#Context-and-project-configuration page to check out how to configure quick filters.
Issue graph filter: link levels
To manage the depth of displayed links between issues in the issue graph, the link level filter is provided. This filter is exclusively available in the issue graph. For instance, by selecting 'Level 1', the graph data will be filtered to exhibit only links to the current issue, which is the one chosen by a click in the issue graph view.
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Selecting ‘Level 2’ will add show links to the issues connected to the current one.
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The maximum number of levels is four.