unknown icon linked to activity

[nono9191]

In one model I'am developping, suddenly an small icon appear near an activity

I don't know what is teh meaning of it
Neither do I know how to turn it on or turn if off
Nothing in the doc

The icon is a small triangle,  color red,  on the top of the activity, with one vertex facing down (to the activity rectangle)
(Difficult to describe here but I can't add an image to this message)
Can somebody help me ?

Thanks to all in advace

My version of EA is Corporate version 6.5 Rev 800

[thomaskilian]

It's a bookmark. Select the element. Press ctrl-space.

Another 0.10 €