Returns the contents of fieldName.
fieldName - any text expression or text field that refers to a field’s name
Important  See Design functions for information about literal text parameters.
Data type returned 
text, number, date, time, timestamp, container
Originated in 
FileMaker Pro 6.0 or earlier
Use this function to get the contents of fieldName, or in any function that uses a field, such as NPV, GetSummary, GetRepetition, or the aggregate functions.
Suppose you have the fields Arrow and Target. Arrow contains the text string Target, and Target contains the text string Bullseye.
GetField(“Arrow”) returns Target. Notice the use of quotation marks around Arrow to indicate the literal string is the fieldName parameter.
GetField(Arrow) returns Bullseye. Notice the absence of quotation marks to indicate the value stored in the Arrow field is the fieldName parameter.
Suppose you have the fields FirstName and LastName. FirstName contains the text string Jane, and LastName contains the text string Public.
GetSummary(GetField(“Field1”), GetField(“Field” & “2”)) performs a summary on the summary field Field1, using a break field of Field2.
Related topics 
Functions reference (category list)
Functions reference (alphabetical list)
About formulas
About functions
Defining calculation fields
Using operators in formulas