#Order number	Originating base	Long abbreviation	Full name	Oneletter-HTML	PDB abbreviation	Category

A	A	A	adenosine	A	A	standard RNA
0A	A	Am	2-O-methyladenosine	:	MRA	modified
1A	A	m1A	1-methyladenosine	"	1MA	modified
2A	A	m2A	2-methyladenosine	/	2MA	modified
3A	A	Arp	2-O-ribosyladenosine(phosphate)	^	RIA	modified
4A	A	m1Am	1,2-O-dimethyladenosine	&oelig;	M2A	modified
5A	A	g6A	N6-glycinylcarbamoyladenosine	&equiv;	UNK	modified
6A	A	m6A	N6-methyladenosine	=	6MA	modified
7A	A	m66A	N6,N6-dimethyladenosine	&zeta;	MA6	modified
7A	A	m62A	N6,N6-dimethyladenosine	&zeta;	UNK	modified
8A	A	m6Am	N6,2-O-dimethyladenosine	&chi;	MMA	modified
9A	A	m66Am	N6,N6,O-2-trimethyladenosine	&eta;	MTA	modified
9A	A	m62Am	N6,N6,O-2-trimethyladenosine	&eta;	MTA	modified
10A	A	I	inosine	I	MRI	modified
11A	A	m1I	1-methylinosine	O	UNK	modified
12A	A	Im	2-O-methylinosine	&le;	1MI	modified
13A	A	m1Im	1,2-O-dimethylinosine	&xi;	UNK	modified
14A	A	t6A	N6-threonylcarbamoyladenosine	6	T6A	modified
15A	A	m6t6A	N6-methyl-N6-threonylcarbamoyladenosine	E	66A	modified
16A	A	ms2t6A	2-methylthio-N6-threonyl_carbamoyladenosine	[	UNK	modified
17A	A	ms2m6A	2-methylthio-N6-methyladenosine	&infin;	SMA	modified
18A	A	ms2hn6A	2-methylthio-N6-hydroxynorvalyl_carbamoyladenosine	&asymp;	UNK	modified
19A	A	i6A	N6-isopentenyladenosine	+	6IA	modified
20A	A	ms2io6A	2-methylthio-N6-(cis-hydroxyisopentenyl) adenosine	&ne;	SIA	modified
21A	A	ms2i6A	2-methylthio-N6-isopentenyladenosine	*	SPA	modified
22A	A	io6A	N6-(cis-hydroxyisopentenyl)adenosine	`	UNK	modified
23A	A	hn6A	N6-hydroxynorvalylcarbamoyladenosine	&radic;	HNA	modified
24A	A	ac6A	N6-acetyladenosine	@	6AA	modified
25A	A	m8A	C8-methyladenosine	@	UNK	modified

C	C	C	cytidine	C	C	standard RNA
0C	C	Cm	2-O-methylcytidine	B	MRC	modified
1C	C	k2C	lysidine	}	UNK	modified
2C	C	s2C	2-thiocytidine	%	2SC	modified
3C	C	m3C	3-methylcytidine	'	3MC	modified
4C	C	m4C	N4-methylcytidine	&nu;	4MC	modified
5C	C	m5C	5-methylcytidine	?	M5C	modified
6C	C	ac4C	N4-acetylcytidine	M	4AC	modified
7C	C	ac4Cm	N4-acetyl-2-O-methylcytidine	&alefsym;	MAC	modified
8C	C	m4Cm	N4,2-O-dimethylcytidine	&lambda;	UNK	modified
9C	C	m44C	N4,N4-dimethylcytidine	@	UNK	modified
9C	C	m42C	N4,N4-dimethylcytidine	@	UNK	modified
10C	C	m44Cm	N4,N4,2-O-trimethylcytidine	&beta;	UNK	modified
10C	C	m42Cm	N4,N4,2-O-trimethylcytidine	&beta;	UNK	modified
11C	C	m5Cm	5,2-O-dimethylcytidine	&tau;	UNK	modified
12C	C	f5C	5-formylcytidine	>	5FC	modified
13C	C	f5Cm	5-formyl-2-O-methylcytidine	째	UNK	modified
14C	C	hm5C	5-hydroxymethylcytidine	&empty;	HMC	modified

G	G	G	guanosine	G	G	standard RNA
0G	G	Gm	2-O-methylguanosine	#	MRG	modified
1G	G	m1G	1-methylguanosine	K	1MG	modified
2G	G	m2G	N2-methylguanosine	L	2MG	modified
3G	G	m22G	N2,N2-dimethylguanosine	R	M2G	modified
4G	G	m22Gm	N2,N2,2-O-trimethylguanosine	|	MTG	modified
5G	G	Grp	2-O-ribosylguanosine(phosphate)	&image;	UNK	modified
6G	G	G+	archaeosine	(	UNK	modified
6G	G	fa7d7G	archaeosine	(	UNK	modified
7G	G	m7G	7-methylguanosine	7	7MG	modified
8G	G	m7m2G	N2,7-dimethylguanosine	&or;	27G	modified
9G	G	m7m22G	N2,N2,7-trimethylguanosine	&ang;	N2G	modified
10G	G	imG	wyosine	&Yuml;	UNK	modified
11G	G	m1Gm	1,2-O-dimethylguanosine	&epsilon;	UNK	modified
12G	G	m2Gm	N2,2-O-dimethylguanosine	&gamma;	MMG	modified
13G	G	mimG	methylwyosine	&sum;	UNK	modified
14G	G	imG-14	4-demethylwyosine	&dagger;	DWG	modified
15G	G	imG2	isowyosine	&supe;	UNK	modified
16G	G	yW	wybutosine	Y	WBG	modified
17G	G	oHyW	hydroxywybutosine	&sube;	UNK	modified
18G	G	oHyWx	undermodified hydroxywybutosine	&scaron;	UNK	modified
19G	G	o2yW	peroxywybutosine	W	UNK	modified
58G	G	yW-58	10-glutamylmethylesterwyosine	@	UNK	modified
72G 	G	yW-72	10-glutamylwyosine	@	UNK	modified
86G 	G	yW-86	10-glutamyl-4-demethylwyosine	@	UNK	modified

Q	G	QtRNA	queuosine	Q	Q	modified
1Q	G	Qbase	Qbase	&there4;	UNK	modified
2Q	G	preQ0tRNA	7-cyano-7-deazaguanosine	&phi;	DCG	modified
3Q	G	preQ1base	preQ1base	&nabla;	UNK	modified
4Q	G	preQ1tRNA	7-aminomethyl-7-deazaguanosine	&notin;	PQ1	modified
5Q	G	oQtRNA	epoxyqueuosine	&sigma;	UNK	modified
6Q	G	galQtRNA	galactosyl-queuosine	9	UNK	modified
7Q	G	manQtRNA	mannosyl-queuosine	8	UNK	modified
8Q	G	gluQtRNA	gluQtRNA	&nsub;	UNK	modified
9Q	G	preQ0base	preQ0base	&psi;	UNK	modified

U	U	U	uridine	U	U	standard RNA
0U	U	Um	2-O-methyluridine	J	MRU	modified
1U	U	Y	pseudouridine	P	13P	modified
2U	U	s2U	2-thiouridine	2	2SU	modified
3U	U	m3U	3-methyluridine	&delta;	3MU	modified
4U	U	s4U	4-thiouridine	4	4SU	modified
5U	U	m5U	5-methyluridine	T	5MU	modified
6U	U	D	dihydrouridine	D	H2U	modified
7U	U	m1Y	1-methylpseudouridine	]	1MP	modified
8U	U	m1acp3Y	1-methyl-3-(3-amino-3-carboxypropyl)pseudouridine	&alpha;	OCU	modified
9U	U	Ym	2-O-methylpseudouridine	Z	MRP	modified
10U	U	m3Y	3-methylpseudouridine	&kappa;	3MP	modified
11U	U	se2U	se2U	&omega;	UNK	modified
12U	U	s2Um	2-thio-2-O-methyluridine	&prod;	MSU	modified
13U	U	m3Um	3,2-O-dimethyluridine	&sigma;	UNK	modified
14U	U	acp3U	3-(3-amino-3-carboxypropyl)uridine	X	UNK	modified
15U	U	acp3Um	3-(3-amino-3-carboxypropyl)methyluridine	&dagger;	UNK	modified
16U	U	m5Um	5,2-O-dimethyluridine	\	2MU	modified
17U	U	m5s2U	5-methyl-2-thiouridine	F	52U	modified
18U	U	f5U	5-formyl-methyluridine	&sub;	UNK	modified
19U	U	f5Um	5-formyl-O-dimethyluridine	&sup;	UNK	modified
20U	U	f5s2U	5-formyl-2-thiouridine	&otimes;	UNK	modified
21U	U	f5se2U	5-formyl-2-selenuoridine	&oplus;	UNK	modified
22U	U	ho5U	5-hydroxyuridine	&prop;	5HU	modified
23U	U	mo5U	5-methoxyuridine	5	UNK	modified
24U	U	nm5U	5-methylaminouridine	&cup;	UNK	modified
25U	U	nm5s2U	5-aminomethyl-2-thiouridine	&int;	SAU	modified
26U	U	nm5se2U	5-aminomethyl-2-selenouridine	&pi;	UNK	modified
27U	U	mnm5U	5-methylaminomethyluridine	{	5AU	modified
28U	U	mnm5s2U	5-methylaminomethyl-2-thiouridine	S	ESU	modified
29U	U	mnm5se2U	5-methylaminomethyl-2-selenouridine	&cong;	SEU	modified
30U	U	cmnm5U	5-carboxymethylaminomethyluridine	!	5DU	modified
31U	U	cmnm5Um	5-carboxymethylaminomethyl-2-O-methyluridine	)	UNK	modified
32U	U	cmnm5s2U	5-carboxymethylaminomethyl-2-thiouridine	$	SCU	modified
33U	U	cmnm5se2U	5-carboxymethylaminomethyl-2-selenouridine	&perp;	UNK	modified
34U	U	cm5U	5-carboxymethyluridine	&loz;	5CU	modified
35U	U	cm5s2U	5-carboxymethyl-2-thiouridine	&weierp;	UNK	modified
36U	U	chm5U	5-(carboxyhydroxymethyl)uridine	&ge;	HCU	modified
37U	U	mcm5U	5-methoxycarbonylmethyluridine	1	MEU	modified
38U	U	mcmo5U	uridine 5-oxyacetic acid methyl ester	&upsilon;	OEU	modified
39U	U	mcm5Um	5-methoxycarbonylmethyl-2-O-methyluridine	&cap;	UNK	modified
40U	U	mcm5s2U	5-methoxycarbonylmethyl-2-thiouridine	3	SMU	modified
41U	U	mchm5U	5-(carboxyhydroxymethyl)uridine methyl ester	,	UNK	modified
42U	U	ncm5U	5-carbamoylmethyluridine	&	BCU	modified
43U	U	ncm5Um	5-carbamoylmethyl-2-O-methyluridine	~	UNK	modified
44U	U	tm5U	5-taurinomethyluridine	&forall;	5TU	modified
45U	U	tm5s2U	5-taurinomethyl-2-thiouridine	&exist;	STU	modified
46U	U	cmo5U	uridine 5-oxyacetic acid	V	OEU	modified
47U	U	m5D	5-methyldihydrouridine	&rho;	DMU	modified

# unknown
UNK	A	?A	Unknown modified adenosine	H	UNK	unknown
UNK	C	?C	Unknown modified cytidine	<	UNK	unknown
UNK	G	?G	Unknown modified guanosine	;	UNK	unknown
UNK	U	?U	Unknown modified uridine	N	UNK	unknown
UNK	A	?dA	Unknown modified desoxyadenosine	H	UNK	unknown
UNK	C	?dC	Unknown modified desoxycytidine	<	UNK	unknown
UNK	G	?dG	Unknown modified desoxyguanosine	;	UNK	unknown
UNK	U	?dU	Unknown modified desoxyuridine	N	UNK	unknown
UNK	X	X	Unknown	.	UNK	unknown
UNK	x	x	No one-letter-abbrev	x	x	unknown
UNK	X	Xm	Unknown 2'OH methylated base	@	UNK	unknown

# Desoxynucleotides
a	A	dA	desoxyadenosine	a	a	standard DNA
g	G	dG	desoxyguanosine	g	g	standard DNA
c	C	dC	desoxycytosine	c	c	standard DNA
t	U	dT	desoxythymidine	t	t	standard DNA

# phosphorylated nucleotides
AMP	A	AMP	Adenosine monophosphate	H	AMP	ligand
ADP	A	ADP	Adenosine diphosphate	H	ADP	ligand
ATP	A	ATP	Adenosine triphosphate	H	ATP	ligand
CMP	C	CMP	Cytidine monophosphate	<	CMP	ligand
CDP	C	CDP	Cytidine diphosphate	<	CDP	ligand
CTP	C	CTP	Cytidine triphosphate	<	CTP	ligand
GMP	G	GMP	Guanosine monophosphate	;	GMP	ligand
GDP	G	GDP	Guanosine diphosphate	;	GDP	ligand
GTP	G	GTP	Guanosine triphosphate	;	GTP	ligand
UMP	U	UMP	Uridine monophosphate	N	UMP	ligand
UDP	U	UDP	Uridine monophosphate	N	UDP	ligand
UTP	U	UTP	Uridine monophosphate	N	UTP	ligand
IMP	G	IMP	Inosine monophosphate	;	IMP	ligand
IDP	G	IDP	Inosine diphosphate	;	IDP	ligand
ITP	G	ITP	Inosine triphosphate	;	ITP	ligand
TMP	U	TMP	Thymine monophosphate	N	TMP	ligand
TDP	U	TDP	Thymine diphosphate	N	TDP	ligand
TTP	U	TTP	Thymine triphosphate	N	TTP	ligand

# desoxy phosphates
AMP	A	dAMP	Deoxyadenosine monophosphate	H	AMP	ligand
ADP	A	dADP	Deoxyadenosine diphosphate	H	ADP	ligand
ATP	A	dATP	Deoxyadenosine triphosphate	H	ATP	ligand
GMP	G	dGMP	Deoxyguanosine monophosphate	;	GMP	ligand
GDP	G	dGDP	Deoxyguanosine diphosphate	;	GDP	ligand
GTP	G	dGTP	Deoxyguanosine triphosphate	;	GTP	ligand
CMP	C	dCMP	Deoxycytydine monophosphate	<	CMP	ligand
CDP	C	dCDP	Deoxycytydine diphosphate	<	CDP	ligand
CTP	C	dCTP	Deoxycytydine triphosphate	<	CTP	ligand
UMP	U	dUMP	Deoxyuridine monophosphate	N	UMP	ligand
UDP	U	dUDP	Deoxyuridine diphosphate	N	UDP	ligand
UTP	U	dUTP	Deoxyuridine triphosphate	N	UTP	ligand
TMP	U	dTMP	Deoxythymine monophosphate	N	TMP	ligand
TDP	U	dTDP	Deoxythymine diphosphate	N	TDP	ligand
TTP	U	dTTP	Deoxythymine triphosphate	N	TTP	ligand

# mRNA-caps
M7GPP_CAP	G	m7Gpp_cap	m7G-diphosphate-cap	x	GDP	cap

# modified phosphate groups
UNK	A	?A_mod_phos	Unknown adenosine phosphate modification	H	UNK	ligand
UNK	C	?C_mod_phos	Unknown cytidine phosphate modification	<	UNK	ligand
UNK	G	?G_mod_phos	Unknown guanosine phosphate modification	;	UNK	ligand
UNK	U	?U_mod_phos	Unknown uridine phosphate modification	N	UNK	ligand
UNK	U	?T_mod_phos	Unknown thymine phosphate modification	N	UNK	ligand

UNK	A	?A_5'amino	Unknown adenosine phosphate modification	H	UNK	ligand
UNK	C	?C_5'amino	Unknown cytidine phosphate modification	<	UNK	ligand
UNK	G	?G_5'amino	Unknown guanosine phosphate modification	;	UNK	ligand
UNK	U	?U_5'amino	Unknown uridine phosphate modification	N	UNK	ligand
UNK	U	?T_5'amino	Unknown thymine phosphate modification	N	UNK	ligand
UNK	U	?Tm_5'amino	Unknown thymine phosphate modification	N	UNK	ligand

UNK	A	?dA_mod_phos	Unknown adenosine phosphate modification	H	UNK	ligand
UNK	C	?dC_mod_phos	Unknown cytidine phosphate modification	<	UNK	ligand
UNK	G	?dG_mod_phos	Unknown guanosine phosphate modification	;	UNK	ligand
UNK	U	?dU_mod_phos	Unknown uridine phosphate modification	N	UNK	ligand
UNK	U	?dT_mod_phos	Unknown thymine phosphate modification	N	UNK	ligand

UNK	A	?A_mod_diphos	Unknown adenosine phosphate modification	H	UNK	ligand
UNK	C	?C_mod_diphos	Unknown cytidine phosphate modification	<	UNK	ligand
UNK	G	?G_mod_diphos	Unknown guanosine phosphate modification	;	UNK	ligand
UNK	U	?U_mod_diphos	Unknown uridine phosphate modification	N	UNK	ligand
UNK	U	?T_mod_diphos	tUnknown thymine phosphate modification	N	UNK	ligand

UNK	A	?dA_mod_diphos	Unknown adenosine phosphate modification	H	UNK	ligand
UNK	C	?dC_mod_diphos	Unknown cytidine phosphate modification	<	UNK	ligand
UNK	G	?dG_mod_diphos	Unknown guanosine phosphate modification	;	UNK	ligand
UNK	U	?dU_mod_diphos	Unknown uridine phosphate modification	N	UNK	ligand
UNK	U	?dT_mod_diphos	Unknown thymine phosphate modification	N	UNK	ligand

# synthetic
#	ms2i6A	A	ms2i6A	2-methylthio-N-6(A2-isopentenyl)-adenosine	x	UNK	synthetic
UNK	G	d8fG	d8fG	x	UNK	synthetic
UNK	G	d8oG	d8oG	x	UNK	synthetic
UNK	U	3meo5mU	3meo5mU	x	UNK	synthetic
UNK	C	3meo5mC	3meo5mC	x	UNK	synthetic
UNK	A	3meoA	3meoA	x	UNK	synthetic
UNK	G	3meoG	3meoG	x	UNK	synthetic
UNK	G	dN72G	dN72G	x	UNK	synthetic
UNK	C	dm5C	dm5C	x	UNK	synthetic
UNK	G	dm8G	dm8G	x	UNK	synthetic
UNK	U	dmo5U	dmo5U	x	UNK	synthetic
UNK	G	dm6G	dm6G	x	UNK	synthetic
UNK	U	tfT	tfT	x	UNK	synthetic
UNK	A	tfA	tfA	x	UNK	synthetic
UNK	C	5nitroC	5nitroC	x	UNK	synthetic
UNK	U	d5nitroU	d5nitroU	x	UNK	synthetic
UNK	U	2mcrabT	2mcrabT	x	UNK	synthetic
UNK	A	N2A	N2A	x	UNK	synthetic
UNK	A	dN2A	dN2A	x	UNK	synthetic
UNK	U	5propU	5propU	x	UNK	synthetic
UNK	U	5propnU	5propnU	x	UNK	synthetic
UNK	U	5propU	5propU	x	UNK	synthetic
UNK	U	2ofluore-m5U	2ofluore-m5U	x	UNK	synthetic
UNK	G	2ofluore-m7G	2ofluore-m7G	x	UNK	synthetic
UNK	C	dethC	dethC	x	UNK	synthetic
UNK	U	5fluoroU	5fluoroU	x	UNK	synthetic
UNK	C	5fluoroC	5fluoroC	x	UNK	synthetic
UNK	X	dhOroP	dhOroP	x	UNK	synthetic
UNK	G	7fluorobenzylG	7fluorobenzylG	x	UNK	synthetic
UNK	C	2oNC	2oNC	x	UNK	synthetic
UNK	C	2oNAcC	2oNAcC	x	UNK	synthetic
UNK	G	disoG	disoG	x	UNK	synthetic
UNK	U	de3T	de3T	x	UNK	synthetic
UNK	U	o6U	o6U	x	UNK	synthetic
UNK	G	2ofluoro-8oG	2ofluoro-8oG	x	UNK	synthetic
UNK	A	3pADP	3pADP	x	UNK	synthetic
UNK	C	23pC	23pC	x	UNK	synthetic
UNK	A	23pA	23pA	x	UNK	synthetic
UNK	G	35pG	35pG	x	UNK	synthetic
UNK	G	d35pG	d35pG	x	UNK	synthetic
UNK	U	d3pT	d3pT	x	UNK	synthetic
UNK	A	d5mpA	d5mpA	x	UNK	synthetic
UNK	A	VA	VA	x	UNK	synthetic
UNK	C	d5mpC	d5mpC	x	UNK	synthetic
UNK	G	phosphonoG	phosphonoG	x	UNK	synthetic
UNK	U	m5Ueth	m5Ueth	x	UNK	synthetic
UNK	U	dmo5U	dmo5U	x	UNK	synthetic
UNK	U	dmh5U	dmh5U	x	UNK	synthetic

#stereoisomers
UNK	U	arabinoseU	Uridine stereoisomer	N	UNK	stereoisomer
UNK	A	arabinoseA	Adenosine stereoisomer	H	UNK	stereoisomer
UNK	G	arabinoseG	Guanosine stereoisomer	;	UNK	stereoisomer
UNK	C	arabinoseC	Cytidine stereoisomer	<	UNK	stereoisomer
UNK	A	alpha-dA	Adenosine stereoisomer	H	UNK	stereoisomer

# Insertion
_	_	_	insertion	_	_	insertion

# Missing residue
-	-	-	missing residue	-	-	missing

# empty space for representing modifications in new nomenclature
# 	 	 	empty space	 	 	 

