docs on data-types

docs/src/tutorial.md

@@ -219,6 +219,18 @@ v1=3, v2=third
 
 ## Writing Excel Files
 
+### Data Types
+
+This package uses the following concrete types when handling XLSX files.
+
+```@docs
+XLSX.CellValueType
+```
+
+- Abstract types of these concrete types are converted to the appropriate concrete type when writing.
+
+- `Nothing` values are converted to `Missing` when writing.
+
 ### Create New Files
 
 Opening a file in `write` mode with `XLSX.openxlsx` will open a new (blank) Excel file for editing.

src/types.jl

@@ -56,6 +56,15 @@ struct CellDataFormat <: AbstractCellDataFormat
     id::UInt
 end
 
+"""
+    CellValueType
+
+Concrete supported data-types.
+
+```julia
+Union{String, Missing, Float64, Int, Bool, Dates.Date, Dates.Time, Dates.DateTime}
+```
+"""
 const CellValueType = Union{String, Missing, Float64, Int, Bool, Dates.Date, Dates.Time, Dates.DateTime}
 
 # CellValue is a Julia type of a value read from a Spreadsheet.