Excel API

msdn - mt616485
dev.office.com/reference/add-ins/requirement-sets/excel-api-requirement-sets

Excel Types

Excel - Ribbon command displaying a dialog
Excel - Ribbon command displaying a task pane
Excel - Task pane displayed initially
Excel - Task pane which can display a dialog
Excel - Shortcut Menu displaying a dialog
Excel - Shortcut Menu displaying a task pane
Excel - Content inserted onto worksheet

Data Types Supported

Text
Matrix (added in Excel 2013, SP1)
Table