You can put anything you want into it, and it jumbles it up amusingly. You can choose how badly it jumbles it.
It was originally used for creature raws and the like, but we started feeding things like books and star trek episodes into it to great effect.
It jumbles it up in such a way that the product is in correct DF raw syntax?
But then how could it understand English syntax as well without any changes?
It doesn't understand syntax much. It creates readable text by virtue of not only using symbol combinations found in the source, but also using them with the same probability that they occur in the source. So the longer the text you feed to it, the better it manages to form coherent sentences.
With DF raws though, it mostly just follows the raw syntax - square brackets for tags, colons separating elements. The results are never actually workable, but they're very fun to read.
((Note: my comments are in double-parentheses. Comments prefaced with -- are from the raws themselves.))[HAS_NEUTRAININGULAR]
[LOOD:BLOOD:BLOOD:LIQUID]
[ANY_TEMPLAN:STANCE_MATEGORY:ADVENDRA]
[APPLY_CREATURE:SHIP]
[PREFSTRUCTURQUOISON]
[ATTACK_FLYING:mid-sized, raven allightly-strel.]
[SITION:A large form othe sponsore:goblenderine
[APPOINTROLLER]
[IMPORTANDY:QUADRUID_ART]
[PET_ENDINGULAR]
[ENDING_POPULAR]
[BIOME:giant chill.]
[REGION:The Bamber]
Just becomestics. Mainlessness.]
A colored. Their small_mammal was long natural man:fox women:bark:bark]
[GENDERGROUND]
[LOOSE_SEA_MONSTRUCK (two heath is declare prized, walks once bite:bite:bite:bite:bite:bite:bite:bites value
[OBJECT:PLANT_TOKEN:grama]
[WOOD_WOOD_BISCUITS]
[ITEM_ARMLESSNESS]
[COLOSS:MAUVE_THICKNESS]
Badgers:grizzly blunt-force cow]
[AMMO:ITEM_ARMLESSNESS]
Crows:red-purple flocks following formation of rocks.]
PLUCKED_LOVEBIRTH]
[INTELLIGATOR] -- they have differ from Wikiped only when burrow]
[TIMBRE:FORESTLINGUISTIC_PET_EXIST]
[ALCOHOL_CREAM]
[TREE_COMBAT:80:900]
A coldest parakeet burrow boominated.
Here, somethods as pedalboars tool.]
Wolve properly.
[NON_MORNING:EVIL]
[AMBUSHTIT_MAP_DESIGN]
happybara
[INST_FIPPLE, PURE, PURE, PIERCING, HARSH_TROLLECTED_IF_SELF]
[NATURE:OLM_MASK:RARE]
[PLANTER][VEGETATIONED]
[TUNING as forest.]
[SAVANNA_TROLL_NUM:TEST_ALBATROLL]
[BASIC_FORTIFIED_IF_EXTREMES:bentgrasp and learn mayhem.
[FUNCTION, SCRATCH COVER]
[GOBBLINGULAR]
[VOLCANO_MINIFORGE]
[CAN_LEGLESS_NECKS:2]
[NIGHTENING:translucentaurs:minotaur:milion]
[ITEMCORPSE_QUADRUPED_NECKS:2]
[NOTHOUGHTLESSNESS]
[OBJECT:PLAYABLE_BURIAL:SKILL:UNTHINKABLED]
can use colossus:broad and AIR_HUNTING, HARMONIC_SERPENTRY]
[NO_THONG:VIBRATES]
[USE_EVIL_ANIMAL:JUSTIFIED_IF_NO_REPRIMAND]
[NAME_FEEL_EMISSION_FACTOR]
[MUSICALLY_ERODE_ENABLE_VERMING:EAR:30:0]
And finally, ultimate weapon.
[AMMO:ITEM:SMALL REGION]