If you use custom metadata in DEVONthink Pro and Server or DEVONthink To Go, you’ve probably used text-based attributes like Single-Line Text. These attributes are defined in DEVONthink’s Settings > Data and commonly accessed in Tools > Inspectors > Info: Data. You can use each type in the ways you want, but here are the features and limitations of each:
- Single-Line Text remembers and lets you choose values you’ve previously typed. You can also add default values in the Data settings. That clears the memory of those previously entered values and only items you’ve defined will be offered. However, unlike a Set, you still can add ad-hoc information too. Note, these impromptu entries will not be remembered so if you want to use the value again, add it to the attribute’s settings.
- Multi-Line Text is exactly as described: text over multiple lines but without any formatting. To create new paragraphs, press ⌥⏎.
- The Rich Text type is similar to the multi-line option, but does allow formatting, e.g., bold and italic text. Create new paragraphs by simply pressing ⏎. You can even press ⌘T to open the Font panel and switch fonts.
- The Identifier is the simplest and strictest type: you enter text, with no formatting, without multiple lines, and no memory of previously entered values. This is often used for static, single-purpose information like software license keys, policy numbers, and similar static values.
- With a Set, you define the only values you can choose in the popup. This lets you strictly control the choices you (or others) have. If you need a new option to choose, add it to the attribute’s settings.
In DEVONthink To Go, you’ll open Settings > Data for definitions. To open a document’s Data inspector, open the Info popup, then tap 
︎ next to General, and choose Data.