I too learnt DTP with PageMaker and used Quark and Interleaf back in the 90s so have played with a few different tools over the years.

The anchors can be displayed by going to File > Options > Display
ObjectAnchors.png
You need to also know what paragraph is anchoring the graphic to fully understand what will happen to your floating graphic as text is edited nearby. If you drag the shape around the page, you may notice the anchor changes paragraphs to stay close to the picture. You can stop that by ticking the 'Lock Anchor' on the dialog where you set the positioning.

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Andrew Lockton
Chrysalis Design, Melbourne Australia