Xcode intellisense meaning of letters in colored boxes like f,T,C,M,P,C,K,# etc

in Xcode this is called "Code Sense". And these icons also exist in Xcode 3.

Red: macros

• # = macro (think #define)

Brown: Core Data / namespace

• C = modeled class
• M = modeled method

• P = modeled property

• N = C++ namespace

Orange: aliased types

• C̲ = Objective-C category
• E = enum
• T = typedef

Green: variables

• B = binding
• ƒ = function
• F = field
• K = constant
• L = local variable
• O = IBOutlet
• V = variable (can be ivar, global var, local var, etc.)
• x = parameter (think f(x))

Blue: methods

• A = IBAction
• M = method
• P = property

Purple: aggregate types

• C = class (Objective-C or C++)
• ₠ = class extension
• Pr = Objective-C protocol
• S = struct
• U = union

You should be able to look up the meanings from the filenames from/Developer/Library/PrivateFrameworks/DVTFoundation.framework/Resources/Xcode.SourceCodeSymbolKind.*.Icon.tiff. Note that, not all icons are used in Code Sense, as these are shared by all Xcode components.