CAML Value Type

AllDayEvent	The all day event flag is used in calendar lists.
Attachments	The URL of an attachment.
Boolean	A boolean indicator with Yes/No.
Calculated	Indicates that the column is a calculated column based on a expression.
Choice	Indicates that the column is choice from a list of items
Computed	Indicates the field's value is dependant on another field's value.
ContentTypeId	A Content Type ID value.
Counter	An internal unique ID's / counter for each item.
Currency	A currency value (its format depends on the locale).
DateTime	A Date and Time field.
File	A file object when used in document libraries.
GridChoice	A rating scale as used in surveys
Guid	A globally unique identifier.
Integer	An integer number field.
Lookup	The field is a lookup which is a choice, however the choice is from another list.
LookupMulti	A lookup field, however multiple selections are allowed.
ModStat	An approval status.
MultiChoice	A choice field, however multiple selections are allowed
Note	Multiple lines of text which can be plain or formatted.
Number	A numerical field which allows decimal places.
PageSeparator	A page separator field, for surveys.
Recurrence	An indicator that identifies the field as a reoccurring calendar event.
Text	A single line of text
ThreadIndex	The ID of a discussion thread.
Threading	Indicates the field supports threading (in discussions).
URL	A Unified Resource Locator (URL) is stored.
User	A person or group.
UserMulti	A person or group, however multiple people or groups can be selected.
WorkflowEventType	Contains the type of workflow history event (used in workflow history list).
WorkflowStatus	The status of a workflow is stored.