NOTES:
Note 1) libpnd is not (currently) as picky as the validator (since it only consumes some values, and will
        sometimes 'trust' bad values in hopes things will just work anyway), but many of the online download
        repositories _will_ use this validator, so it is probably a good idea to make your PXMLs conform! For
        example the <package> block is currently not used/required for libpnd to work.
Note 2) These points aside -- anything passing the validator should pass into libpnd just fine; PXML.xmls that
        do not pass the validator may well work with libpnd, depending on the nature of the rejection --
        if the PXML.xml is just bad, fix it! But if the validator rejects the PXML.xml on grounds of
        bad categories or line ordering or whatever, then libpnd will 'accept' the application, but may
        massage things to work (eg add the application into the category 'Other' or do some more obscure things).
Note 3) minimenu and xfce and other Freedesktop Standard adhering applications may actually be pickier about
        some things than the validator -- the validator will verify the categories and subcategories are
        known to the Freedesktop spec, but does not validate that a FD subcategory actually belongs to the
        listed parent category. 

How to read this doc:
* Every entry comes with a cardinality. Here is the meaning of those:
  =1: this block is required exactly once
  <=1: up to one of those blocks is allowed (0 or 1)
  >=1: at least one of those is allowed, more are possible but optional
  >=0: optional element that can be added in unlimited numbers
* The actually used 'tag's are always displayed in this form: <tag>.
* Arguments are always marked either as optional or required and mention what allowed values are. At the bottom
  of this doc is an explanation of most of those values. If you see [abc|xyz] it means that either 'abc' or
  'xyz' are valid values.
* In general 'order' of elements does not matter unless stated otherwise.
* If a block is used, the content is usually *NOT* allowed to be empty. So if you don't want to use something,
  don't specify that argument!


Now, onto the actual specification:

1) at the root there is *exactly* one <PXML> block
2) inside this PXML block is exactly =1 <package> block
        (required) id=DUMBFOLDERNAME
3) inside this PXML block are >=1 <application> blocks
        (required) id=DUMBFOLDERNAME
        (optional) appdata=DUMBFOLDERNAME


inside the <package> block:
1) =1 <author>
        (required) name=TEXT
        (optional) website=anyURI
        (optional) email=EMAILADDRESS
2) =1 <version>
        (required) major=VERSION_NR
        (required) minor=VERSION_NR
        (required) release=VERSION_NR
        (required) build=VERSION_NR
        (optional) type=[alpha|beta|release]
3) =1 <titles> (order matters!)
        (required) =1 <description lang="en_US">TEXT</description> (enforcing that an en_US string is available, has to be listed first)
        (optional) >=1 <title>TEXT</title>
                        (required) lang=LANGCODE ( [a-zA-Z]{2,3}(_[a-zA-Z0-9]{2,3})* )
4) <=1 <descriptions> (order matters!)
        (required) =1 <description lang="en_US">TEXT</description> (enforcing that an en_US string is available, has to be listed first)
        (optional) >=0 <description>TEXT</description>
                        (required) lang=LANGCODE ( [a-zA-Z]{2,3}(_[a-zA-Z0-9]{2,3})* )
5) <=1 <icon>
        (required) src=DUMBPATH


inside each <application> block:
1) =1 <exec>
        (required) command=TOKEN
        (optional) arguments=TOKEN
        (optional) background=BOOLEAN
        (optional) startdir=DUMBPATH
        (optional) standalone=BOOLEAN
        (optional) x11=[req|stop|ignore]
2) =1 <author>
        (required) name=TEXT
        (optional) website=anyURI
        (optional) email=EMAILADDRESS
3) =1 <version>
        (required) major=VERSION_NR
        (required) minor=VERSION_NR
        (required) release=VERSION_NR
        (required) build=VERSION_NR
        (optional) type=[alpha|beta|release] (if not specified 'release' will be assumed)
4) <=1 <osversion>
        (required) major=VERSION_NR
        (required) minor=VERSION_NR
        (required) release=VERSION_NR
        (required) build=VERSION_NR
5) =1 <titles> (order matters!)
        (required) =1 <title lang="en_US">TEXT</title> (enforcing that an en_US string is available, has to be listed first)
        (optional) >=0 <title>TEXT</title>
                        (required) lang=LANGCODE ( [a-zA-Z]{2,3}(_[a-zA-Z0-9]{2,3})* )
6) <=1 <title lang="en_US">TEXT</title> (meant for compatibility with <=HF6, only en_US supported)
7) <=1 <descriptions> (order matters!)
        (required) =1 <description lang="en_US">TEXT</description> (enforcing that an en_US string is available, has to be listed first)
        (optional) >=0 <description>TEXT</description>
                        (required) lang=LANGCODE ( [a-zA-Z]{2,3}(_[a-zA-Z0-9]{2,3})* )
8) <=1 <description lang="en_US">TEXT</description> (meant for compatibility with <=HF6, only en_US supported)
9) <=1 <icon>
        (required) src=DUMBPATH
10)=1 <licenses>
        (required) >=1 <license>
                        (required) name=TEXT
                        (required) url=anyURI
                        (required) sourcecodeurl=anyURI
11)<=1 <previewpics>
        (optional) >=0 <pic>
                        (required) src=DUMBPATH
12)<=1 <info>
        (required) name=TEXT
        (required) type=[text/html|text/plain]
        (required) src=DUMBPATH
13)=1 <categories>
        (required) >=1 <category>
                        (required) name=fdoCategory
                        (optional) <subcategory>
                                  (required) name=fdoSubCategory
14)<=1 <associations>
        (required) >=1 <association>
                        (required) name=TEXT
                        (required) filetype=TOKEN
                        (required) arguments=TOKEN
15)<=1 <clockspeed>
        (required) frequency=positiveInteger



Filetype/variable explanation:
anyURI: should be some URL, no idea what exactly XML accepts there... (XML variable 'anyURI'!)
BOOLEAN: 0 or 1 or true or false (XML variable 'boolean'!)
DUMBFOLDERNAME: TEXT without ?>:/
DUMBPATH: TEXT without ?>:
EMAILADDRESS: [^@]+@[^\.]+\..+      in normal lang: something with an @ in the middle and some domain like thingie
LANGCODE: [a-zA-Z]{2,3}(_[a-zA-Z0-9]{2,3})*   example: en, eng, en_US, fur_IT
TEXT: The normalizedString data type also contains characters, but the XML processor will remove line feeds, carriage returns, and tab characters. (XML variable 'normalizedString'!)
TOKEN: The token data type also contains characters, but the XML processor will remove line feeds, carriage returns, tabs, leading and trailing spaces, and multiple spaces. (XML variable 'token'!)
VERSION_NR: [a-zA-Z0-9+-]*   example: 1, a, +svn, -svn, 123456789123456789

fdoCategory=AudioVideo|Audio|Video|Development|Education|Game|Graphics|Network|Office
fdoSubCategory=Building|Debugger|IDE|GUIDesigner|Profiling|RevisionControl|Translation|Calendar|ContactManagement|Database|Dictionary|Chart|Email|Finance|FlowChart|PDA|ProjectManagement|Presentation|Spreadsheet|WordProcessor|2DGraphics|VectorGraphics|RasterGraphics|3DGraphics|Scanning|OCR|Photography|Publishing|Viewer|TextTools|DesktopSettings|HardwareSettings|Printing|PackageManager|Dialup|InstantMessaging|Chat|IRCClient|FileTransfer|HamRadio|News|P2P|RemoteAccess|Telephony|TelephonyTools|VideoConference|WebBrowser|WebDevelopment|Midi|Mixer|Sequencer|Tuner|TV|AudioVideoEditing|Player|Recorder|DiscBurning|ActionGame|AdventureGame|ArcadeGame|BoardGame|BlocksGame|CardGame|KidsGame|LogicGame|RolePlaying|Simulation|SportsGame|StrategyGame|Art|Construction|Music|Languages|Science|ArtificialIntelligence|Astronomy|Biology|Chemistry|ComputerScience|DataVisualization|Economy|Electricity|Geography|Geology|Geoscience|History|ImageProcessing|Literature|Math|NumericalAnalysis|MedicalSoftware|Physics|Robotics|Sports|ParallelComputing|Amusement|Archiving|Compression|Electronics|Emulator|Engineering|FileTools|FileManager|TerminalEmulator|Filesystem|Monitor|Security|Accessibility|Calculator|Clock|TextEditor|Documentation|Core|KDE|GNOME|GTK|Qt|Motif|Java|ConsoleOnly
