Manifold tables can utilize the following data types for fields.
boolean 
TRUE or FALSE, also expressed as 1 or 0 
datetime 
A calendar date (day, month, year) and time (hour, minute, second, millisecond) ranging from January 3, 0001, 00:00:00.000 to December 31, 9999, 23:59:59.999 
float32 
32 bit floating point number with a range of 1.5 x 1045 to 3.4 x 1038 
float32x2 float32x3 float32x4 
Vectorsof 2, 3 or 4 numbers, each of which is a float32 
float64 
64 bit floating point number with a range of 5.0 x 10324 to 1.7 x 10308 
float64x2 float64x3 float64x4 
Vectors of 2, 3 or 4 numbers, each of which is a float64

geom geommfd 
Manifold geometry. geom is the native Manifold geometry type. geommfd is the equivalent written in binary for storage in external databases. 
geomwkb 
WKB geometry 
int8 
8 bit signed integer for values from 128 to 127 
int8x2 int8x3 int8x4 
Vectors of 2, 3 or 4 numbers, each of which is an int8 
int16 
16 bit signed integer for values from 32,768 to 32,767 
int16x2 int16x3 int16x4 
Vectors of 2, 3 or 4 numbers, each of which is an int16 
int32 
32 bit signed integer for values from 2,147,483,648 to 2,147,483,647 
int32x2 int32x3 int32x4 
Vectors of 2, 3 or 4 numbers, each of which is an int32 
int64 
64 bit signed integer for values from 9,223,372,036,854,775,808 to 9,223,372,036,854,775,807 
int64x2 int64x3 int64x4 
Vectors of 2, 3 or 4 numbers, each of which is an int64 
nvarchar 
Variable length Unicode text using UNICODE UCS2 character set, two bytes per character. 2 GB maximum storage size for a total of 1 GB characters. 
tile 
A Manifold array of numbers of specified size, such as 128 x 128, where each number in the array is an allowed Manifold numeric type, including vector numeric types such as uint8x3. 
uint8 
8 bit unsigned integer for values from 0 to 255 
uint8x2 uint8x3 uint8x4 
Vectors of 2, 3 or 4 numbers, each of which is a uint8 
uint16 
16 bit unsigned integer for values from 0 to 65,535 
uint16x2 uint16x3 uint16x4 
Vectors of 2, 3 or 4 numbers, each of which is a uint16 
uint32 
32 bit unsigned integer for values from 0 to 4,294,967,295 
uint32x2 uint32x3 uint32x4 
Vectors of 2, 3 or 4 numbers, each of which is a uint32 
uint64 
64 bit unsigned integer for values from 0 to 18,446,744,073,709,551,615 
uint64x2 uint64x3 uint64x4 
Vectors of 2, 3 or 4 numbers, each of which is a uint64 
uuid 
Universally Unique IDentifier (UUID), a 128 bit value represented by a text string of lowercase hexadecimal digits in standard form of groups of digits separated by hyphens. Each UUID is unique. 
varbinary 
Variable length binary data. Maximum storage size is 2 GB 
varchar 
Variable length nonUnicode text, one byte per character. 2 GB maximum storage size for a total of 2 GB characters. 
Tooltips on table column headers will show the name of the field as well as the data type:
Dataports for databases expose all text fields as NVARCHAR (Unicode) even if they are stored as VARCHAR. Attempting to create a VARCHAR field will create it as VARCHAR on the database, but the field will look like an NVARCHAR data type in Manifold. What VARCHAR means varies between data sources and converting between different meanings frequently loses data, so this convention by Manifold helps to preserve data.
Consider an example: In Manifold, VARCHAR means 'characters in the currently active codepage, whatever that currently active codepage may be.' However, in databases VARCHAR usually means 'characters in the codepage associated with the field / table / database'. If we connect to a database, we can ask it to return data as VARCHAR, and the database might return data in a German codepage if a German code page was used for that field. If we then try to use that data as VARCHAR in Manifold on an English system, the characters will be interpreted wrongly. That will affect both correct display of the characters as well as comparisons and orderings.
Different client systems use different ways of dealing with such issues. Manifold 8, for example, allows setting a codepage for the field. However, the end result of such adaptations is to convert the data in all codepages different from the default code page into Unicode and then handle data as Unicode. If Unicode ends up being the intermediate form, it is better, as Manifold now does, to simply do the conversion as close to the data as possible.
See related comments in the DBMS Data Sources  Notes topic.
Why "N"varchar?  Why the n prefix for Unicode versions of varchar? Before Unicode got traction, character sets for different languages were known as National Character data sets. MySQL still calls these types national character and national varchar. Manifold and SQL Server call these nvarchar (SQL Server adds an nchar type to match SQL Server's char type), and Oracle calls them nchar and nvarchar2. PostgreSQL and DB2 have char and varchar without "N" versions. See the Collations topic for more on how national languages are handled.
Computed fields  Fields in tables can be computed fields, which automatically calculate a value for the field based on an expression. See the Example: Add a Computed Field to a Table topic for a step by step example.
Geometry collections  Reading geometry collection values automatically merges individual values of the same underlying type used in Manifold geometry, such as area, line or point, with differences between subtypes such as line and multiline being ignored. The result of the merge is returned. This applies to all data which support geometry collection values, including WKB, GeoJSON, JSON, native geometry in databasespecific formats, and so on.
Reading geometry collection values with individual values of mixed underlying types automatically converts areas to lines and lines to points in order to return all coordinates. Example: reading a geometry collection with an area and several points will return a multipoint containing all coordinates of all individual values.
3D conversions  Geometry values with mixed 2Dand 3Dcoordinates in GML, GeoJSON, and TopoJSON are automatically converted to 3D with 2D coordinates padded with zeros.