# Hidden Formulas > [!info] > For a complete (or at least periodically updated list) of hidden formulas, view [this page](https://community.coda.io/t/a-somewhat-of-a-documentation-of-hidden-formulas-added-mechanics-of-nested-buttons/9831). ## Safe - `_Bold()` - `_Italicize()` - `_Underline()` - `_Strikethrough()` - `_Code()` - `_Highlight()` — you can’t specify color with this formula, but [you can use the `Color()` formula to add colored highlight](https://community.coda.io/t/a-somewhat-of-a-documentation-of-hidden-formulas-added-advanced-usage-of-the-color-formula/9831/9) > [!warning] > When using the formatting formulas above, you cannot use the `+` concatenation operator. You **must** use the long-form `Concatenate()` function. ## Somewhat Safe - `_RichText()` — seems to be useless, basically does the same as `Concatenate()` - `_Color()` - `All()` - `Any()` - `Identity` — returns input value (so it is basically useless) - `_MERGE` — “Deeply merges objects” - `_DELAY` — “Returns a value after some delay” - `_CREATE_ERROR` — “Create an error” - `_NoOp()` [action] — no operation to use in IF statements for an action - `Activate()` [action] — brings referenced element into focus ## Danger Zone Unstable or untested, you should implement [fail-safe procedures](https://community.coda.io/t/a-somewhat-of-a-documentation-of-hidden-formulas/9831/4) before using these: - `_MergeConditionalFormats` — “Deeply merges objects” - `_PROJECT_COLUMN_FOR_ROWIDS` — “Filters rows in a table to the set of rows with ids matching the values” - `_HASH_MATCH` — “Filters on column equivalence on some or all matching columns” - `_TRUE` — not sure why it exists along with just `True()`. - `_RandomImpl` — “Generate a random number” - `_FAKE_ARRAY` — “Returns an array with a schema” - `_FAKE_OBJECT` — “Returns an object with a schema” - `_WRAP_INVALID_FORMULA` — “Used to wrap an invalid user formula so the invalid input does not break AST parsing.” - `_DEREF_OBJECT` — “Dereferences the given path” - `_DEREF` — “Dereferences the given input with the given reference” - `_DEREF_OPT` — “Dereferences the given input with the given reference” - `_ROW_KEY` — “Returns the reference key for the given row” - `_SORTED_SEEK` — “Filters on column equivalence on some or all matching columns” - `_RANDOMIZE_CURRENTLOCATION` — “Random travel” - `FormatCurrency()` - `FormatDateTime()` - `FormatDuration()` - `FormatNumber()` - `FormatPercent()` - `FormatTime()` - `ATTACHMENTCONTROL` - `BUTTON` - `CHECKBOX` - `DATEPICKER` - `DATERANGEPICKER` - `FORMULACONTROL` - `MULTISELECT` - `SELECT` - `SCALE` - `SLIDER` - `HTML()` - `BLOB` — for system use only - `STDEV` and `STDEVP` - `ToHtml` - `Project` — “Projects one or more columns from the given result” - `CurrentLocation` - `RegexExtract` - `Quartile()` — “Outputs the item nearest to a specified quartile from a list of items” - `Card()` — “Renders a read-only card control” - `DuplicateSection()` [action] - `Xhr()` [action] — make an XHR request to an URL with arbitrary method and body - `RefreshPack()` [action] - `StartSync()` [action] - `FinishSync()` [action] - `PieChart()` - `LineChart()` - `BarChart()` - `PieChartAggregate()` - `Histogram()` - `GoogleDirections()` - `GoogleMap()` - `LaTeX()`