The svn:executable property is used to control a versioned file's filesystem-level execute permission bit in a semi-automated way. This property has no defined values-its mere presence indicates a desire that the execute permission bit be kept enabled by Subversion. Removing this property will restore full control of the execute bit back to the operating system. On many operating systems, the ability to execute a file as a command is governed by the presence of an execute permission bit. This bit usually defaults to being disabled, and must be explicitly enabled by the user for each file that needs it. In a working copy, new files are being created all the time as new versions of existing files are received during an update. This means that you might enable the execute bit on a file, then update your working copy, and if that file was changed as part of the update, its execute bit might get disabled. So, Subversion provides the svn:executable property as a way to keep the execute bit enabled. This property has no effect on filesystems that have no concept of an executable permission bit, such as FAT32 and NTFS. Also, although it has no defined values, Subversion will force its value to * when setting this property. Finally, this property is valid only on files, not on directories The svn:mime-type property serves many purposes in Subversion. Besides being a general-purpose storage location for a file's Multipurpose Internet Mail Extensions (MIME) classification, the value of this property determines some behavioral characteristics of Subversion itself. The svn:ignore property contains a list of file patterns which certain Subversion operations will ignore. Perhaps the most commonly used special property, it works in conjunction with the globalignores run-time configuration option (see the section called "Config") to filter unversioned files and directories out of commands like svn status, svn add, and svn import. The rationale behind the svn:ignore property is easily explained. Subversion does not assume that every file or subdirectory in a working copy directory is intended for version control. Resources must be explicitly placed under Subversion's management using the svn add or svn import commands. As a result, there are often many resources in a working copy that are not versioned. Subversion has the ability to substitute keywords-pieces of useful, dynamic information about a versioned file-into the contents of the file itself. Keywords generally describe information about the last time the file was known to be modified. Because this information changes each time the file changes, and more importantly, just after the file changes, it is a hassle for any process except the version control system to keep the data completely up-to-date. Left to human authors, the information would inevitably grow stale. Unless otherwise noted using a versioned file's svn:mime-type property, Subversion assumes the file contains human-readable data. Generally speaking, Subversion only uses this knowledge to determine if contextual difference reports for that file are possible. Otherwise, to Subversion, bytes are bytes. The svn:externals property contains instructions for Subversion to populate a versioned directory with one or more other checked-out Subversion working copies. The svn:special property is the only svn: property that isn't meant to be directly set or modified by users. Subversion automatically sets this property whenever a "special" object is scheduled for addition, such as a symbolic link. Standard subversion properties