Page Comparison

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Name	Outward Description	Inward Description
Gantt: finish-finish	has to be finished together with	has to be finished together with
Gantt: finish-start	has to be done before	has to be done after
Gantt: start-finish	earliest end is start of	start is earliest end of
Gantt: start-start	has to be started together with	has to be started together with

Step-by-step guide

move the mouse over the Gantt bar of the source issue: a blue bubble will occur on the right having a tooltip "add link"
click on the blue bubble to start issue linking for Gantt-dependency
move mouse over the Gantt bar of the target issue and a blue bubble on the left will occur
use the default issue link type as displayed on the right hand of the left blue bubble or select your preferred type out of the combo box
finally, click on the left blue bubble to link both issues using the selected issue link type
on the Gantt-Chart both linked issues will be displayed a "connected" using the look and style as defined for the related issue link type
Additionally, depending on the type (Gantt-dependency) the target issue's planning dates will be adjusted if re-scheduling is enabled (default)

Info
If you use JIRA's standard feature to create links between issues, no automatic re-scheduling will take place, but the issues will be displayed in a linked way using the defined coloring and style.