Hubcards are intended to be short and contain only the most important information. However some people might want to read more - either about sub-topics or related topics.
While editing a card, you can create a link by selecting the text you want to link from, and clicking the link icon. This will reveal a link editor that lets you select an existing card, or create a new card.
Click "edit" on the "My Test Card" you created earlier, select "Elvis" and then click the link button. Now click "New Subcard: Elvis" to create a link to a new sub-card about Elvis.
Once you've saved the change, you'll be able to click the link to see an empty card about Elvis. You can now click "Edit" to fill in content for that card.
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