You are looking at the HTML representation of the TXT format.
HTML is good for debugging, but is unsuitable for application use.
Specify the format parameter to change the output format.
To see the non HTML representation of the TXT format, set format=txt.
See the complete documentation, or API help for more information.
Array
(
    [query] => Array
        (
            [namespaces] => Array
                (
                    [-2] => Array
                        (
                            [id] => -2
                            [case] => first-letter
                            [*] => Media
                            [canonical] => Media
                        )

                    [-1] => Array
                        (
                            [id] => -1
                            [case] => first-letter
                            [*] => Special
                            [canonical] => Special
                        )

                    [0] => Array
                        (
                            [id] => 0
                            [case] => first-letter
                            [*] => 
                            [content] => 
                        )

                    [1] => Array
                        (
                            [id] => 1
                            [case] => first-letter
                            [*] => Talk
                            [subpages] => 
                            [canonical] => Talk
                        )

                    [2] => Array
                        (
                            [id] => 2
                            [case] => first-letter
                            [*] => User
                            [subpages] => 
                            [canonical] => User
                        )

                    [3] => Array
                        (
                            [id] => 3
                            [case] => first-letter
                            [*] => User talk
                            [subpages] => 
                            [canonical] => User talk
                        )

                    [4] => Array
                        (
                            [id] => 4
                            [case] => first-letter
                            [*] => XC3 Wiki
                            [subpages] => 
                            [canonical] => Project
                        )

                    [5] => Array
                        (
                            [id] => 5
                            [case] => first-letter
                            [*] => XC3 Wiki talk
                            [subpages] => 
                            [canonical] => Project talk
                        )

                    [6] => Array
                        (
                            [id] => 6
                            [case] => first-letter
                            [*] => File
                            [canonical] => File
                        )

                    [7] => Array
                        (
                            [id] => 7
                            [case] => first-letter
                            [*] => File talk
                            [subpages] => 
                            [canonical] => File talk
                        )

                    [8] => Array
                        (
                            [id] => 8
                            [case] => first-letter
                            [*] => MediaWiki
                            [subpages] => 
                            [canonical] => MediaWiki
                        )

                    [9] => Array
                        (
                            [id] => 9
                            [case] => first-letter
                            [*] => MediaWiki talk
                            [subpages] => 
                            [canonical] => MediaWiki talk
                        )

                    [10] => Array
                        (
                            [id] => 10
                            [case] => first-letter
                            [*] => Template
                            [canonical] => Template
                        )

                    [11] => Array
                        (
                            [id] => 11
                            [case] => first-letter
                            [*] => Template talk
                            [subpages] => 
                            [canonical] => Template talk
                        )

                    [12] => Array
                        (
                            [id] => 12
                            [case] => first-letter
                            [*] => Help
                            [subpages] => 
                            [canonical] => Help
                        )

                    [13] => Array
                        (
                            [id] => 13
                            [case] => first-letter
                            [*] => Help talk
                            [subpages] => 
                            [canonical] => Help talk
                        )

                    [14] => Array
                        (
                            [id] => 14
                            [case] => first-letter
                            [*] => Category
                            [canonical] => Category
                        )

                    [15] => Array
                        (
                            [id] => 15
                            [case] => first-letter
                            [*] => Category talk
                            [subpages] => 
                            [canonical] => Category talk
                        )

                    [102] => Array
                        (
                            [id] => 102
                            [case] => first-letter
                            [*] => Property
                            [canonical] => Property
                        )

                    [103] => Array
                        (
                            [id] => 103
                            [case] => first-letter
                            [*] => Property talk
                            [subpages] => 
                            [canonical] => Property talk
                        )

                    [104] => Array
                        (
                            [id] => 104
                            [case] => first-letter
                            [*] => Type
                            [canonical] => Type
                        )

                    [105] => Array
                        (
                            [id] => 105
                            [case] => first-letter
                            [*] => Type talk
                            [subpages] => 
                            [canonical] => Type talk
                        )

                    [106] => Array
                        (
                            [id] => 106
                            [case] => first-letter
                            [*] => Form
                            [canonical] => Form
                        )

                    [107] => Array
                        (
                            [id] => 107
                            [case] => first-letter
                            [*] => Form talk
                            [subpages] => 
                            [canonical] => Form talk
                        )

                    [108] => Array
                        (
                            [id] => 108
                            [case] => first-letter
                            [*] => Concept
                            [canonical] => Concept
                        )

                    [109] => Array
                        (
                            [id] => 109
                            [case] => first-letter
                            [*] => Concept talk
                            [canonical] => Concept talk
                        )

                    [274] => Array
                        (
                            [id] => 274
                            [case] => first-letter
                            [*] => Widget
                            [canonical] => Widget
                        )

                    [275] => Array
                        (
                            [id] => 275
                            [case] => first-letter
                            [*] => Widget talk
                            [subpages] => 
                            [canonical] => Widget talk
                        )

                    [420] => Array
                        (
                            [id] => 420
                            [case] => first-letter
                            [*] => Layer
                            [canonical] => Layer
                        )

                    [421] => Array
                        (
                            [id] => 421
                            [case] => first-letter
                            [*] => Layer talk
                            [canonical] => Layer talk
                        )

                    [500] => Array
                        (
                            [id] => 500
                            [case] => first-letter
                            [*] => Projects
                            [canonical] => Projects
                        )

                    [501] => Array
                        (
                            [id] => 501
                            [case] => first-letter
                            [*] => Projects Talk
                            [canonical] => Projects Talk
                        )

                    [502] => Array
                        (
                            [id] => 502
                            [case] => first-letter
                            [*] => Session
                            [canonical] => Session
                        )

                    [503] => Array
                        (
                            [id] => 503
                            [case] => first-letter
                            [*] => Session Talk
                            [canonical] => Session Talk
                        )

                    [504] => Array
                        (
                            [id] => 504
                            [case] => first-letter
                            [*] => Assembly
                            [canonical] => Assembly
                        )

                    [505] => Array
                        (
                            [id] => 505
                            [case] => first-letter
                            [*] => Assembly Talk
                            [canonical] => Assembly Talk
                        )

                    [506] => Array
                        (
                            [id] => 506
                            [case] => first-letter
                            [*] => Hackerspace
                            [subpages] => 
                            [canonical] => Hackerspace
                        )

                    [507] => Array
                        (
                            [id] => 507
                            [case] => first-letter
                            [*] => Hackerspace Talk
                            [subpages] => 
                            [canonical] => Hackerspace Talk
                        )

                    [508] => Array
                        (
                            [id] => 508
                            [case] => first-letter
                            [*] => Continent
                            [canonical] => Continent
                        )

                    [509] => Array
                        (
                            [id] => 509
                            [case] => first-letter
                            [*] => Continent Talk
                            [canonical] => Continent Talk
                        )

                    [510] => Array
                        (
                            [id] => 510
                            [case] => first-letter
                            [*] => Country
                            [canonical] => Country
                        )

                    [511] => Array
                        (
                            [id] => 511
                            [case] => first-letter
                            [*] => Country Talk
                            [canonical] => Country Talk
                        )

                    [512] => Array
                        (
                            [id] => 512
                            [case] => first-letter
                            [*] => City
                            [canonical] => City
                        )

                    [513] => Array
                        (
                            [id] => 513
                            [case] => first-letter
                            [*] => City Talk
                            [canonical] => City Talk
                        )

                    [514] => Array
                        (
                            [id] => 514
                            [case] => first-letter
                            [*] => Static
                            [subpages] => 
                            [canonical] => Static
                        )

                    [515] => Array
                        (
                            [id] => 515
                            [case] => first-letter
                            [*] => Static Talk
                            [subpages] => 
                            [canonical] => Static Talk
                        )

                    [516] => Array
                        (
                            [id] => 516
                            [case] => first-letter
                            [*] => Room
                            [canonical] => Room
                        )

                    [517] => Array
                        (
                            [id] => 517
                            [case] => first-letter
                            [*] => Room Talk
                            [canonical] => Room Talk
                        )

                    [518] => Array
                        (
                            [id] => 518
                            [case] => first-letter
                            [*] => AssemblyInfo
                            [subpages] => 
                            [canonical] => AssemblyInfo
                        )

                    [519] => Array
                        (
                            [id] => 519
                            [case] => first-letter
                            [*] => AssemblyInfo Talk
                            [canonical] => AssemblyInfo Talk
                        )

                    [520] => Array
                        (
                            [id] => 520
                            [case] => first-letter
                            [*] => Calendar
                            [canonical] => Calendar
                        )

                    [521] => Array
                        (
                            [id] => 521
                            [case] => first-letter
                            [*] => Calendar Talk
                            [canonical] => Calendar Talk
                        )

                    [522] => Array
                        (
                            [id] => 522
                            [case] => first-letter
                            [*] => Lightning
                            [canonical] => Lightning
                        )

                    [523] => Array
                        (
                            [id] => 523
                            [case] => first-letter
                            [*] => Lightning Talk
                            [canonical] => Lightning Talk
                        )

                    [524] => Array
                        (
                            [id] => 524
                            [case] => first-letter
                            [*] => Link
                            [canonical] => Link
                        )

                    [525] => Array
                        (
                            [id] => 525
                            [case] => first-letter
                            [*] => Link Talk
                            [canonical] => Link Talk
                        )

                    [526] => Array
                        (
                            [id] => 526
                            [case] => first-letter
                            [*] => Cluster
                            [canonical] => Cluster
                        )

                    [527] => Array
                        (
                            [id] => 527
                            [case] => first-letter
                            [*] => Cluster Talk
                            [canonical] => Cluster Talk
                        )

                )

        )

)