This means that in addition to being well-formed, the documents conform to a defined schema.
1	This	this	PRON	DEM-SG	Number=Sing|PronType=Dem	2	nsubj	_	_
2	means	mean	VERB	PRES	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	0	root	_	_
3	that	that	SCONJ	_	_	12	mark	_	_
4	in	in	ADP	_	_	5	case	_	_
5	addition	addition	NOUN	SG-NOM	Number=Sing	12	obl	_	_
6	to	to	ADP	_	_	8	case	_	_
7	being	be	AUX	ING	Tense=Pres|VerbForm=Part	8	cop	_	_
8	well-formed	well-formed	ADJ	POS	Degree=Pos	5	amod	_	SpaceAfter=No
9	,	,	PUNCT	Comma	_	5	punct	_	_
10	the	the	DET	DEF	Definite=Def|PronType=Art	11	det	_	_
11	documents	document	NOUN	PL-NOM	Number=Plur	12	nsubj	_	_
12	conform	conform	VERB	PRES	Mood=Ind|Tense=Pres|VerbForm=Fin	2	ccomp	_	_
13	to	to	ADP	_	_	16	case	_	_
14	a	a	DET	IND-SG	Definite=Ind|PronType=Art	16	det	_	_
15	defined	define	ADJ	PASS	Case=Nom	16	amod	_	_
16	schema	schema	NOUN	SG-NOM	Number=Sing	12	obl	_	SpaceAfter=No
17	.	.	PUNCT	Period	_	2	punct	_	_
