diff --git a/t/gff_syntax/in/45_test.gff b/t/gff_syntax/in/45_test.gff
new file mode 100644
index 00000000..4b9a164f
--- /dev/null
+++ b/t/gff_syntax/in/45_test.gff
@@ -0,0 +1,8 @@
+BK063639.1	tpg	tRNA	1637	1705	.	+	.	ID=rna-BK063639.1:1637..1705;gbkey=tRNA;product=tRNA-Ile
+BK063639.1	tpg	exon	1637	1705	.	+	.	ID=exon-BK063639.1:1637..1705-1;Parent=rna-BK063639.1:1637..1705;gbkey=tRNA;product=tRNA-Ile
+BK063639.1	tpg	CDS	1790	2779	.	+	0	ID=cds-DBA43806.1;Dbxref=NCBI_GP:DBA43806.1;Name=DBA43806.1;gbkey=CDS;product=ND2;protein_id=DBA43806.1;transl_table=5
+BK063639.1	tpg	tRNA	2768	2840	.	-	.	ID=rna-BK063639.1:2768..2840;gbkey=tRNA;product=tRNA-Cys
+BK063639.1	tpg	exon	2768	2840	.	-	.	ID=exon-BK063639.1:2768..2840-1;Parent=rna-BK063639.1:2768..2840;gbkey=tRNA;product=tRNA-Cys
+BK063639.1	tpg	tRNA	3030	3098	.	-	.	ID=rna-BK063639.1:3030..3098;gbkey=tRNA;product=tRNA-Trp
+BK063639.1	tpg	exon	3030	3098	.	-	.	ID=exon-BK063639.1:3030..3098-1;Parent=rna-BK063639.1:3030..3098;gbkey=tRNA;product=tRNA-Trp
+BK063639.1	tpg	CDS	3114	4658	.	+	0	ID=cds-DBA43807.1;Dbxref=NCBI_GP:DBA43807.1;Name=DBA43807.1;gbkey=CDS;product=COX1;protein_id=DBA43807.1;transl_table=5
diff --git a/t/gff_syntax/in/46_test.gff b/t/gff_syntax/in/46_test.gff
new file mode 100644
index 00000000..8444f9f4
--- /dev/null
+++ b/t/gff_syntax/in/46_test.gff
@@ -0,0 +1,6 @@
+BK063639.1	tpg	CDS	1790	2779	.	+	0	ID=cds-DBA43806.1;Dbxref=NCBI_GP:DBA43806.1;Name=DBA43806.1;gbkey=CDS;product=ND2;protein_id=DBA43806.1;transl_table=5
+BK063639.1	tpg	tRNA	2768	2840	.	-	.	ID=rna-BK063639.1:2768..2840;gbkey=tRNA;product=tRNA-Cys
+BK063639.1	tpg	exon	2768	2840	.	-	.	ID=exon-BK063639.1:2768..2840-1;Parent=rna-BK063639.1:2768..2840;gbkey=tRNA;product=tRNA-Cys
+BK063639.1	tpg	tRNA	3030	3098	.	-	.	ID=rna-BK063639.1:3030..3098;gbkey=tRNA;product=tRNA-Trp
+BK063639.1	tpg	exon	3030	3098	.	-	.	ID=exon-BK063639.1:3030..3098-1;Parent=rna-BK063639.1:3030..3098;gbkey=tRNA;product=tRNA-Trp
+BK063639.1	tpg	CDS	3114	4658	.	+	0	ID=cds-DBA43807.1;Dbxref=NCBI_GP:DBA43807.1;Name=DBA43807.1;gbkey=CDS;product=COX1;protein_id=DBA43807.1;transl_table=5
diff --git a/t/gff_syntax/out/45_correct_output.gff b/t/gff_syntax/out/45_correct_output.gff
new file mode 100644
index 00000000..2e766092
--- /dev/null
+++ b/t/gff_syntax/out/45_correct_output.gff
@@ -0,0 +1,18 @@
+##gff-version 3
+BK063639.1	AGAT	gene	1637	1705	.	+	.	ID=agat-gene-1;gbkey=tRNA;product=tRNA-Ile
+BK063639.1	tpg	tRNA	1637	1705	.	+	.	ID=rna-BK063639.1:1637..1705;Parent=agat-gene-1;gbkey=tRNA;product=tRNA-Ile
+BK063639.1	tpg	exon	1637	1705	.	+	.	ID=exon-BK063639.1:1637..1705-1;Parent=rna-BK063639.1:1637..1705;gbkey=tRNA;product=tRNA-Ile
+BK063639.1	AGAT	gene	1790	2779	.	+	.	ID=agat-gene-4;Dbxref=NCBI_GP:DBA43806.1;Name=DBA43806.1;gbkey=CDS;product=ND2;protein_id=DBA43806.1;transl_table=5
+BK063639.1	AGAT	mRNA	1790	2779	.	+	.	ID=agat-rna-1;Parent=agat-gene-4;Dbxref=NCBI_GP:DBA43806.1;Name=DBA43806.1;gbkey=CDS;product=ND2;protein_id=DBA43806.1;transl_table=5
+BK063639.1	AGAT	exon	1790	2779	.	+	.	ID=agat-exon-1;Parent=agat-rna-1;Dbxref=NCBI_GP:DBA43806.1;Name=DBA43806.1;gbkey=CDS;product=ND2;protein_id=DBA43806.1;transl_table=5
+BK063639.1	tpg	CDS	1790	2779	.	+	0	ID=cds-DBA43806.1;Parent=agat-rna-1;Dbxref=NCBI_GP:DBA43806.1;Name=DBA43806.1;gbkey=CDS;product=ND2;protein_id=DBA43806.1;transl_table=5
+BK063639.1	AGAT	gene	2768	2840	.	-	.	ID=agat-gene-2;gbkey=tRNA;product=tRNA-Cys
+BK063639.1	tpg	tRNA	2768	2840	.	-	.	ID=rna-BK063639.1:2768..2840;Parent=agat-gene-2;gbkey=tRNA;product=tRNA-Cys
+BK063639.1	tpg	exon	2768	2840	.	-	.	ID=exon-BK063639.1:2768..2840-1;Parent=rna-BK063639.1:2768..2840;gbkey=tRNA;product=tRNA-Cys
+BK063639.1	AGAT	gene	3030	3098	.	-	.	ID=agat-gene-3;gbkey=tRNA;product=tRNA-Trp
+BK063639.1	tpg	tRNA	3030	3098	.	-	.	ID=rna-BK063639.1:3030..3098;Parent=agat-gene-3;gbkey=tRNA;product=tRNA-Trp
+BK063639.1	tpg	exon	3030	3098	.	-	.	ID=exon-BK063639.1:3030..3098-1;Parent=rna-BK063639.1:3030..3098;gbkey=tRNA;product=tRNA-Trp
+BK063639.1	AGAT	gene	3114	4658	.	+	.	ID=agat-gene-5;Dbxref=NCBI_GP:DBA43807.1;Name=DBA43807.1;gbkey=CDS;product=COX1;protein_id=DBA43807.1;transl_table=5
+BK063639.1	AGAT	mRNA	3114	4658	.	+	.	ID=agat-rna-2;Parent=agat-gene-5;Dbxref=NCBI_GP:DBA43807.1;Name=DBA43807.1;gbkey=CDS;product=COX1;protein_id=DBA43807.1;transl_table=5
+BK063639.1	AGAT	exon	3114	4658	.	+	.	ID=agat-exon-2;Parent=agat-rna-2;Dbxref=NCBI_GP:DBA43807.1;Name=DBA43807.1;gbkey=CDS;product=COX1;protein_id=DBA43807.1;transl_table=5
+BK063639.1	tpg	CDS	3114	4658	.	+	0	ID=cds-DBA43807.1;Parent=agat-rna-2;Dbxref=NCBI_GP:DBA43807.1;Name=DBA43807.1;gbkey=CDS;product=COX1;protein_id=DBA43807.1;transl_table=5
diff --git a/t/gff_syntax/out/46_correct_output.gff b/t/gff_syntax/out/46_correct_output.gff
new file mode 100644
index 00000000..7c0c10a6
--- /dev/null
+++ b/t/gff_syntax/out/46_correct_output.gff
@@ -0,0 +1,15 @@
+##gff-version 3
+BK063639.1	AGAT	gene	1790	2779	.	+	.	ID=agat-gene-3;Dbxref=NCBI_GP:DBA43806.1;Name=DBA43806.1;gbkey=CDS;product=ND2;protein_id=DBA43806.1;transl_table=5
+BK063639.1	AGAT	mRNA	1790	2779	.	+	.	ID=agat-rna-1;Parent=agat-gene-3;Dbxref=NCBI_GP:DBA43806.1;Name=DBA43806.1;gbkey=CDS;product=ND2;protein_id=DBA43806.1;transl_table=5
+BK063639.1	AGAT	exon	1790	2779	.	+	.	ID=agat-exon-1;Parent=agat-rna-1;Dbxref=NCBI_GP:DBA43806.1;Name=DBA43806.1;gbkey=CDS;product=ND2;protein_id=DBA43806.1;transl_table=5
+BK063639.1	tpg	CDS	1790	2779	.	+	0	ID=cds-DBA43806.1;Parent=agat-rna-1;Dbxref=NCBI_GP:DBA43806.1;Name=DBA43806.1;gbkey=CDS;product=ND2;protein_id=DBA43806.1;transl_table=5
+BK063639.1	AGAT	gene	2768	2840	.	-	.	ID=agat-gene-1;gbkey=tRNA;product=tRNA-Cys
+BK063639.1	tpg	tRNA	2768	2840	.	-	.	ID=rna-BK063639.1:2768..2840;Parent=agat-gene-1;gbkey=tRNA;product=tRNA-Cys
+BK063639.1	tpg	exon	2768	2840	.	-	.	ID=exon-BK063639.1:2768..2840-1;Parent=rna-BK063639.1:2768..2840;gbkey=tRNA;product=tRNA-Cys
+BK063639.1	AGAT	gene	3030	3098	.	-	.	ID=agat-gene-2;gbkey=tRNA;product=tRNA-Trp
+BK063639.1	tpg	tRNA	3030	3098	.	-	.	ID=rna-BK063639.1:3030..3098;Parent=agat-gene-2;gbkey=tRNA;product=tRNA-Trp
+BK063639.1	tpg	exon	3030	3098	.	-	.	ID=exon-BK063639.1:3030..3098-1;Parent=rna-BK063639.1:3030..3098;gbkey=tRNA;product=tRNA-Trp
+BK063639.1	AGAT	gene	3114	4658	.	+	.	ID=agat-gene-4;Dbxref=NCBI_GP:DBA43807.1;Name=DBA43807.1;gbkey=CDS;product=COX1;protein_id=DBA43807.1;transl_table=5
+BK063639.1	AGAT	mRNA	3114	4658	.	+	.	ID=agat-rna-2;Parent=agat-gene-4;Dbxref=NCBI_GP:DBA43807.1;Name=DBA43807.1;gbkey=CDS;product=COX1;protein_id=DBA43807.1;transl_table=5
+BK063639.1	AGAT	exon	3114	4658	.	+	.	ID=agat-exon-2;Parent=agat-rna-2;Dbxref=NCBI_GP:DBA43807.1;Name=DBA43807.1;gbkey=CDS;product=COX1;protein_id=DBA43807.1;transl_table=5
+BK063639.1	tpg	CDS	3114	4658	.	+	0	ID=cds-DBA43807.1;Parent=agat-rna-2;Dbxref=NCBI_GP:DBA43807.1;Name=DBA43807.1;gbkey=CDS;product=COX1;protein_id=DBA43807.1;transl_table=5