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Universal Type Identifier
UTI: com.dekorra.eazydraw
UTI: com.dekorra.eazydraw.graphic
File Typing, a Brief History

File typing has been a problem for software developers and users since the first box of punch cards had a job name with processing codes scribbled across its top. The Classic Mac OS used two 32-bit integers, usually expressed as four-character codes to identify a type and creator code. While this naming space or set of addresses filled up over a decade or so, other operating systems used a less defined convention of identifying a type with a dot and three letter extension. In 2001 Apple took a "Next Step" and changed from type and creator to dot/extension with the expansion from 3 letters to unlimited number of letters. The transition necessitated by co-existence of the Classic OS 9 and OS X as well as Carbon, Cocoa, and even Unix heritage applications caused a great deal of confusion for developers and users. This prevented a smooth and uniform adoption of extended extension typing. The primary reason for adopting file name extensions as stated by Steve Jobs at the 2001 developer's conference was because the other operating systems used the approach. That apparently didn't work out.

Over this same period a system called MIME types have been used primarily for MIME-encapsulate or tagged data for Safari and Mail. This system is partially supported by macOS and info.plist for application bundles. But extended MIME attributes were needed to properly use this convention for typing and application bundles did not support the information. MIME is really a non-starter for file format typing and was not really adopted in the macOS environment.

Around 2008 with QuickLook and Spotlight, Apple OS X began moving to a more "thought out" typing solution, called Uniform Type Identifiers (UTI - but don't google just UTI as that will take you to your Urologist's home page). Now with Mountain Lion, UTI's are used throughout the macOS technology, including iCloud, the Finder, QuickLook, Revisions and other modules.

Uniform Type Identifiers

The broad definition of a UTI is a system to "uniquely identify a class of entities considered to have a type". This is the "broad" definition. We are interested primarily in file formats or data on the macOS file system and pasteboard. As technology evolves this system will likely expand to other identifiably typed entities such as disk volumes, folders, and symbolic links.

UTIs are designed to go beyond the limitations of name extensions and type / creator codes. They are unique, using a simple system based on registered internet domain names. UTIs have no restriction on length, lifting confusion of 3 letter conflicts and if desired they can be human readable and translated to provide readable clarity in several languages. They are Extensible, a well defined system is provided for adding new types and extending or collapsing a definition scope. A clear hierarchy can be used to define new types as sub-types of other defined types. And all this can be accomplished safely with or without the blessing or registration of an organizing body or controlling corporate interests such as the Adobe domain over the PDF format.

Ground Rules

A UTI is a text string that can contain numbers, letters, hyphens, and periods, plus any Unicode characters above the ASCII range. Standard types have a "public." prefix. In our world only Apple can define the "public." identifiers. Some that they have specified are: "public.data" (top/root of the tree), "public.text", "public.image" etc. See the diagram above to better understand the relationships.

A unique name for a file type is constructed by reversing a registered domain name. For EazyDraw this involves our historic corporate identity "Dekorra Optics, LLC" which leads to the designation "com.dekorra.eazydraw.xxxx" for EazyDraw file types. We have four formats. Two are human readable formats which are based on Apple pList and two are more compact binary formats base on Cocoa data archiver. This leads to the UTI's which we define: "com.dekorra.eazydraw.graphic", "com.dekorra.eazydraw.binary", "com.dekorra.eazydraw.libtext", and "com.dekorra.eazydraw.libbinary". The first two are the plist and binary formats for EazyDraw drawing files. The last two are the plist and binary formats for EazyDraw drawing element libraries. These four types are registered with macOS and the Finder by appropriate entries in the EazyDraw application bundle, info.plist file. The diagram at the top of this page shows this information in graphic form.

Other Drawing Types

EazyDraw provides icons and assignment information for SVG and AutoCad *.dxf files. The icon files for these drawing types are identified to macOS in the EazyDraw App pList file and the icons (*.icns) are bundled with the EazyDraw application. This means that these file types, will then have an icon for the Finder to use. Other Apps on your Mac may duplicate this uti identification and the Finder may select a display icon from an App other than EazyDraw, so you may see different icons than those showing in EazyDraw's doucmenation and video tutorials.

Mountain Lion:

EazyDraw Retro provides icons and assignment information for MacDrawII, MacDrawPro, ClarisDraw drawings, ClarisDraw libraries, AppleWorks *.cwk files and the AutoCad *.dxf files. The icon files for these drawing types are identified to macOS in the EazyDraw pList file and the icons are bundled with the application. This means that these file types will show in the Finder even if these creator application has never been installed on the system.

Other Creator Codes:

Creator codes are no longer used on Mountain Lion.

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