What are the assignment options to the field? | SAP ABAP

i. Direct assignment of data types, field length, short text to a field.
ii. Data element assignment to a field.
iii. An input check(check table) for a field can be defined with a foreign key.
iv. A search help can be assigned to a field.
v. Reference field or reference table must be specified for a table field that holds currency or quantity type value.