GTM Ultimate Stack
Read the links in a GTM dependency map
What fires, blocks, listens for and uses mean, where dataLayer events come from, why built-in variables appear, and what an item with no links is telling you.
Four link types, read both ways
Every link joins two items and reads differently from each end:
- fires / fired by: a trigger in a tag's firing triggers.
- blocks / blocked by: a trigger in a tag's exceptions.
- listens for / listened for by: a Custom Event trigger and the dataLayer event it waits for.
- uses / used by: a {{variable}} referenced anywhere in a tag's settings, a trigger's conditions or another variable, such as a lookup table's input.
A checklist of the four link types and what creates each one.
Where dataLayer events come from
An event appears when a Custom Event trigger's condition says the event equals a fixed name, such as generate_lead. A trigger that matches events with a pattern is shown with the pattern as its event label. Click, page view, form and timer triggers don't wait for a named event, so they have none, and that's correct, not a gap. An event name built from a variable isn't a fixed name, so it isn't drawn either.
Two panels: Custom Event triggers with a fixed or pattern event name get an event node, while click, page view and variable-named triggers don't.
Built-in variables are dependencies too
GTM keeps built-in variables such as Page URL, Click Element and Event separately from your own. The map draws a built-in as soon as something references it, because a trigger that reads {{Page Path}} depends on it as much as on any variable you created. Turning a built-in off breaks what uses it.
An item with no links
Nothing leads to it and it leads nowhere. For a trigger, that usually means no tag uses it. For a variable, nothing references it. For a tag, it has no triggers. Before you call it dead, check what the map doesn't draw: a setup or cleanup tag runs through tag sequencing, and a trigger can be a member of a Trigger Group. Neither is drawn as a link.
A trigger with nothing leading to it and nothing it leads to, marked as isolated.
The map and the usage verdicts
Inventory & Cleanup gives every item a usage verdict: in use, only inactive users or orphaned. The map is how you see why. An item marked Only inactive users is linked only to something paused; an orphaned one has no links at all. Read the usage verdicts covers the verdicts.
Questions about links
Why is a lookup table linked to another variable?
It reads that variable as its input. Variables that read variables are linked with uses.
Does the map show what a tag sends to GA4?
It shows which variables the tag reads. What GA4 receives is checked by the GTM ↔ GA4 Parity Checker.
Why does an event show a pattern instead of a name?
Its trigger matches events with a regular expression. The pattern is the closest thing to a name.
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