diff --git a/align.c b/align.c
index 808804b..4bcc439 100644
--- a/align.c
+++ b/align.c
@@ -222,7 +222,7 @@ static inline int mm_get_hplen_back(const mm_idx_t *mi, uint32_t rid, uint32_t x
 
 static inline void mm_adjust_minier(const mm_idx_t *mi, uint8_t *const qseq0[2], mm128_t *a, int32_t *r, int32_t *q)
 {
-	if (mi->is_hpc) {
+	if (mi->flag & MM_I_HPC) {
 		const uint8_t *qseq = qseq0[a->x>>63];
 		int i, c;
 		*q = (int32_t)a->y;
@@ -351,14 +351,14 @@ static void mm_align1(void *km, const mm_mapopt_t *opt, const mm_idx_t *mi, int
 	int32_t rs1, qs1, re1, qe1;
 	int8_t mat[25];
 
-	if (is_sr) assert(!mi->is_hpc); // HPC won't work with SR because with HPC we can't easily tell if there is a gap
+	if (is_sr) assert(!(mi->flag & MM_I_HPC)); // HPC won't work with SR because with HPC we can't easily tell if there is a gap
 
 	r2->cnt = 0;
 	if (r->cnt == 0) return;
 	ksw_gen_simple_mat(5, mat, opt->a, opt->b);
 	bw = (int)(opt->bw * 1.5 + 1.);
 
-	if (is_sr && !mi->is_hpc) {
+	if (is_sr && !(mi->flag & MM_I_HPC)) {
 		mm_max_stretch(opt, r, a, &as1, &cnt1);
 		rs = (int32_t)a[as1].x + 1 - (int32_t)(a[as1].y>>32&0xff);
 		qs = (int32_t)a[as1].y + 1 - (int32_t)(a[as1].y>>32&0xff);
@@ -470,7 +470,7 @@ static void mm_align1(void *km, const mm_mapopt_t *opt, const mm_idx_t *mi, int
 
 	for (i = is_sr? cnt1 - 1 : 1; i < cnt1; ++i) { // gap filling
 		if ((a[as1+i].y & (MM_SEED_IGNORE|MM_SEED_TANDEM)) && i != cnt1 - 1) continue;
-		if (is_sr && !mi->is_hpc) {
+		if (is_sr && !(mi->flag & MM_I_HPC)) {
 			re = (int32_t)a[as1 + i].x + 1;
 			qe = (int32_t)a[as1 + i].y + 1;
 		} else mm_adjust_minier(mi, qseq0, &a[as1 + i], &re, &qe);
diff --git a/index.c b/index.c
index 93c5e21..3766fb7 100644
--- a/index.c
+++ b/index.c
@@ -31,19 +31,19 @@ typedef struct mm_idx_bucket_s {
 void mm_idxopt_init(mm_idxopt_t *opt)
 {
 	memset(opt, 0, sizeof(mm_idxopt_t));
-	opt->k = 15, opt->w = 10, opt->is_hpc = 0;
+	opt->k = 15, opt->w = 10, opt->flag = 0;
 	opt->bucket_bits = 14;
 	opt->mini_batch_size = 50000000;
 	opt->batch_size = 4000000000ULL;
 }
 
-mm_idx_t *mm_idx_init(int w, int k, int b, int is_hpc)
+mm_idx_t *mm_idx_init(int w, int k, int b, int flag)
 {
 	mm_idx_t *mi;
 	if (k*2 < b) b = k * 2;
 	if (w < 1) w = 1;
 	mi = (mm_idx_t*)calloc(1, sizeof(mm_idx_t));
-	mi->w = w, mi->k = k, mi->b = b, mi->is_hpc = is_hpc;
+	mi->w = w, mi->k = k, mi->b = b, mi->flag = flag;
 	mi->B = (mm_idx_bucket_t*)calloc(1<<b, sizeof(mm_idx_bucket_t));
 	if (!(mm_dbg_flag & 1)) mi->km = km_init();
 	return mi;
@@ -89,7 +89,7 @@ void mm_idx_stat(const mm_idx_t *mi)
 {
 	int i, n = 0, n1 = 0;
 	uint64_t sum = 0, len = 0;
-	fprintf(stderr, "[M::%s] kmer size: %d; skip: %d; is_HPC: %d; #seq: %d\n", __func__, mi->k, mi->w, mi->is_hpc, mi->n_seq);
+	fprintf(stderr, "[M::%s] kmer size: %d; skip: %d; is_hpc: %d; #seq: %d\n", __func__, mi->k, mi->w, mi->flag&MM_I_HPC, mi->n_seq);
 	for (i = 0; i < mi->n_seq; ++i)
 		len += mi->seq[i].len;
 	for (i = 0; i < 1<<mi->b; ++i)
@@ -214,7 +214,7 @@ static void mm_idx_post(mm_idx_t *mi, int n_threads)
 #include "bseq.h"
 
 typedef struct {
-	int mini_batch_size, keep_name;
+	int mini_batch_size;
 	uint64_t batch_size, sum_len;
 	mm_bseq_file_t *fp;
 	mm_idx_t *mi;
@@ -266,7 +266,7 @@ static void *worker_pipeline(void *shared, int step, void *in)
 			for (i = 0; i < s->n_seq; ++i) {
 				mm_idx_seq_t *seq = &p->mi->seq[p->mi->n_seq];
 				uint32_t j;
-				if (p->keep_name) {
+				if (!(p->mi->flag & MM_I_NO_NAME)) {
 					seq->name = (char*)kmalloc(p->mi->km, strlen(s->seq[i].name) + 1);
 					strcpy(seq->name, s->seq[i].name);
 				} else seq->name = 0;
@@ -288,7 +288,7 @@ static void *worker_pipeline(void *shared, int step, void *in)
         step_t *s = (step_t*)in;
 		for (i = 0; i < s->n_seq; ++i) {
 			mm_bseq1_t *t = &s->seq[i];
-			mm_sketch(0, t->seq, t->l_seq, p->mi->w, p->mi->k, t->rid, p->mi->is_hpc, &s->a);
+			mm_sketch(0, t->seq, t->l_seq, p->mi->w, p->mi->k, t->rid, p->mi->flag&MM_I_HPC, &s->a);
 			free(t->seq); free(t->name);
 		}
 		free(s->seq); s->seq = 0;
@@ -301,16 +301,15 @@ static void *worker_pipeline(void *shared, int step, void *in)
     return 0;
 }
 
-mm_idx_t *mm_idx_gen(mm_bseq_file_t *fp, int w, int k, int b, int is_hpc, int mini_batch_size, int n_threads, uint64_t batch_size, int keep_name)
+mm_idx_t *mm_idx_gen(mm_bseq_file_t *fp, int w, int k, int b, int flag, int mini_batch_size, int n_threads, uint64_t batch_size)
 {
 	pipeline_t pl;
 	if (fp == 0 || mm_bseq_eof(fp)) return 0;
 	memset(&pl, 0, sizeof(pipeline_t));
 	pl.mini_batch_size = mini_batch_size < batch_size? mini_batch_size : batch_size;
-	pl.keep_name = keep_name;
 	pl.batch_size = batch_size;
 	pl.fp = fp;
-	pl.mi = mm_idx_init(w, k, b, is_hpc);
+	pl.mi = mm_idx_init(w, k, b, flag);
 
 	kt_pipeline(n_threads < 3? n_threads : 3, worker_pipeline, &pl, 3);
 	if (mm_verbose >= 3)
@@ -323,13 +322,13 @@ mm_idx_t *mm_idx_gen(mm_bseq_file_t *fp, int w, int k, int b, int is_hpc, int mi
 	return pl.mi;
 }
 
-mm_idx_t *mm_idx_build(const char *fn, int w, int k, int is_hpc, int n_threads) // a simpler interface
+mm_idx_t *mm_idx_build(const char *fn, int w, int k, int flag, int n_threads) // a simpler interface
 {
 	mm_bseq_file_t *fp;
 	mm_idx_t *mi;
 	fp = mm_bseq_open(fn);
 	if (fp == 0) return 0;
-	mi = mm_idx_gen(fp, w, k, 14, is_hpc, 1<<18, n_threads, UINT64_MAX, 1);
+	mi = mm_idx_gen(fp, w, k, 14, flag, 1<<18, n_threads, UINT64_MAX);
 	mm_bseq_close(fp);
 	return mi;
 }
@@ -344,7 +343,7 @@ void mm_idx_dump(FILE *fp, const mm_idx_t *mi)
 	uint32_t x[5];
 	int i;
 
-	x[0] = mi->w, x[1] = mi->k, x[2] = mi->b, x[3] = mi->n_seq, x[4] = mi->is_hpc;
+	x[0] = mi->w, x[1] = mi->k, x[2] = mi->b, x[3] = mi->n_seq, x[4] = mi->flag;
 	fwrite(MM_IDX_MAGIC, 1, 4, fp);
 	fwrite(x, 4, 5, fp);
 	for (i = 0; i < mi->n_seq; ++i) {
@@ -476,10 +475,10 @@ mm_idx_t *mm_idx_reader_read(mm_idx_reader_t *r, int n_threads)
 	mm_idx_t *mi;
 	if (r->is_idx) {
 		mi = mm_idx_load(r->fp.idx);
-		if (mi && mm_verbose >= 2 && (mi->k != r->opt.k || mi->w != r->opt.w || mi->is_hpc != r->opt.is_hpc))
+		if (mi && mm_verbose >= 2 && (mi->k != r->opt.k || mi->w != r->opt.w || (mi->flag&MM_I_HPC) != (r->opt.flag&MM_I_HPC)))
 			fprintf(stderr, "[WARNING]\033[1;31m Indexing parameters (-k, -w or -H) overridden by parameters used in the prebuilt index.\033[0m\n");
 	} else
-		mi = mm_idx_gen(r->fp.seq, r->opt.w, r->opt.k, r->opt.bucket_bits, r->opt.is_hpc, r->opt.mini_batch_size, n_threads, r->opt.batch_size, 1);
+		mi = mm_idx_gen(r->fp.seq, r->opt.w, r->opt.k, r->opt.bucket_bits, r->opt.flag, r->opt.mini_batch_size, n_threads, r->opt.batch_size);
 	if (mi) {
 		if (r->fp_out) mm_idx_dump(r->fp_out, mi);
 		++r->n_parts;
diff --git a/main.c b/main.c
index c233b55..648b0df 100644
--- a/main.c
+++ b/main.c
@@ -6,7 +6,7 @@
 #include "mmpriv.h"
 #include "getopt.h"
 
-#define MM_VERSION "2.5-r572"
+#define MM_VERSION "2.5-r573-dirty"
 
 #ifdef __linux__
 #include <sys/resource.h>
@@ -94,7 +94,7 @@ int main(int argc, char *argv[])
 	while ((c = getopt_long(argc, argv, opt_str, long_options, &long_idx)) >= 0) {
 		if (c == 'w') ipt.w = atoi(optarg);
 		else if (c == 'k') ipt.k = atoi(optarg);
-		else if (c == 'H') ipt.is_hpc = 1;
+		else if (c == 'H') ipt.flag |= MM_I_HPC;
 		else if (c == 'd') fnw = optarg; // the above are indexing related options, except -I
 		else if (c == 'r') opt.bw = (int)mm_parse_num(optarg);
 		else if (c == 't') n_threads = atoi(optarg);
diff --git a/map.c b/map.c
index 086f357..6330f88 100644
--- a/map.c
+++ b/map.c
@@ -64,29 +64,29 @@ int mm_set_opt(const char *preset, mm_idxopt_t *io, mm_mapopt_t *mo)
 		mm_idxopt_init(io);
 		mm_mapopt_init(mo);
 	} else if (strcmp(preset, "ava-ont") == 0) {
-		io->is_hpc = 0, io->k = 15, io->w = 5;
+		io->flag = 0, io->k = 15, io->w = 5;
 		mo->flag |= MM_F_AVA | MM_F_NO_SELF;
 		mo->min_chain_score = 100, mo->pri_ratio = 0.0f, mo->max_gap = 10000, mo->max_chain_skip = 25;
 	} else if (strcmp(preset, "ava-pb") == 0) {
-		io->is_hpc = 1, io->k = 19, io->w = 5;
+		io->flag |= MM_I_HPC, io->k = 19, io->w = 5;
 		mo->flag |= MM_F_AVA | MM_F_NO_SELF;
 		mo->min_chain_score = 100, mo->pri_ratio = 0.0f, mo->max_gap = 10000, mo->max_chain_skip = 25;
 	} else if (strcmp(preset, "map10k") == 0 || strcmp(preset, "map-pb") == 0) {
-		io->is_hpc = 1, io->k = 19;
+		io->flag |= MM_I_HPC, io->k = 19;
 	} else if (strcmp(preset, "map-ont") == 0) {
-		io->is_hpc = 0, io->k = 15;
+		io->flag = 0, io->k = 15;
 	} else if (strcmp(preset, "asm5") == 0) {
-		io->is_hpc = 0, io->k = 19, io->w = 19;
+		io->flag = 0, io->k = 19, io->w = 19;
 		mo->a = 1, mo->b = 19, mo->q = 39, mo->q2 = 81, mo->e = 3, mo->e2 = 1, mo->zdrop = 200;
 		mo->min_dp_max = 200;
 		mo->best_n = 50;
 	} else if (strcmp(preset, "asm10") == 0) {
-		io->is_hpc = 0, io->k = 19, io->w = 19;
+		io->flag = 0, io->k = 19, io->w = 19;
 		mo->a = 1, mo->b = 9, mo->q = 16, mo->q2 = 41, mo->e = 2, mo->e2 = 1, mo->zdrop = 200;
 		mo->min_dp_max = 200;
 		mo->best_n = 50;
 	} else if (strcmp(preset, "short") == 0 || strcmp(preset, "sr") == 0) {
-		io->is_hpc = 0, io->k = 21, io->w = 11;
+		io->flag = 0, io->k = 21, io->w = 11;
 		mo->flag |= MM_F_SR | MM_F_FRAG_MODE | MM_F_NO_PRINT_2ND | MM_F_2_IO_THREADS;
 		mo->pe_ori = 0<<1|1; // FR
 		mo->a = 2, mo->b = 8, mo->q = 12, mo->e = 2, mo->q2 = 24, mo->e2 = 1;
@@ -104,7 +104,7 @@ int mm_set_opt(const char *preset, mm_idxopt_t *io, mm_mapopt_t *mo)
 		mo->max_occ = 5000;
 		mo->mini_batch_size = 50000000;
 	} else if (strcmp(preset, "splice") == 0 || strcmp(preset, "cdna") == 0) {
-		io->is_hpc = 0, io->k = 15, io->w = 5;
+		io->flag = 0, io->k = 15, io->w = 5;
 		mo->flag |= MM_F_SPLICE | MM_F_SPLICE_FOR | MM_F_SPLICE_REV | MM_F_SPLICE_FLANK;
 		mo->max_gap = 2000, mo->max_gap_ref = mo->bw = 200000;
 		mo->a = 1, mo->b = 2, mo->q = 2, mo->e = 1, mo->q2 = 32, mo->e2 = 0;
@@ -173,7 +173,7 @@ static void collect_minimizers(const mm_mapopt_t *opt, const mm_idx_t *mi, int n
 	int i, j, n, sum = 0;
 	b->mini.n = 0;
 	for (i = n = 0; i < n_segs; ++i) {
-		mm_sketch(b->km, seqs[i], qlens[i], mi->w, mi->k, i, mi->is_hpc, &b->mini);
+		mm_sketch(b->km, seqs[i], qlens[i], mi->w, mi->k, i, mi->flag&MM_I_HPC, &b->mini);
 		for (j = n; j < b->mini.n; ++j)
 			b->mini.a[j].y += sum << 1;
 		if (opt->sdust_thres > 0) // mask low-complexity minimizers
diff --git a/minimap.h b/minimap.h
index 0eb279f..45a8f30 100644
--- a/minimap.h
+++ b/minimap.h
@@ -26,6 +26,10 @@
 #define MM_F_SPLICE_FLANK  0x40000
 #define MM_F_SOFTCLIP      0x80000
 
+#define MM_I_HPC          0x1
+#define MM_I_NO_SEQ       0x2
+#define MM_I_NO_NAME      0x4
+
 #define MM_IDX_MAGIC   "MMI\2"
 
 #define MM_MAX_SEG       255
@@ -46,7 +50,7 @@ typedef struct {
 } mm_idx_seq_t;
 
 typedef struct {
-	int32_t b, w, k, is_hpc;
+	int32_t b, w, k, flag;
 	uint32_t n_seq;            // number of reference sequences
 	mm_idx_seq_t *seq;         // sequence name, length and offset
 	uint32_t *S;               // 4-bit packed sequence
@@ -80,7 +84,7 @@ typedef struct {
 
 // indexing and mapping options
 typedef struct {
-	short k, w, is_hpc, bucket_bits;
+	short k, w, flag, bucket_bits;
 	int mini_batch_size;
 	uint64_t batch_size;
 } mm_idxopt_t;
@@ -269,7 +273,7 @@ int mm_map_file_frag(const mm_idx_t *idx, int n_segs, const char **fn, const mm_
 
 // deprecated APIs for backward compatibility
 void mm_mapopt_init(mm_mapopt_t *opt);
-mm_idx_t *mm_idx_build(const char *fn, int w, int k, int is_hpc, int n_threads);
+mm_idx_t *mm_idx_build(const char *fn, int w, int k, int flag, int n_threads);
 
 #ifdef __cplusplus
 }
diff --git a/python/cmappy.pxd b/python/cmappy.pxd
index e3444a9..de969a4 100644
--- a/python/cmappy.pxd
+++ b/python/cmappy.pxd
@@ -5,7 +5,7 @@ cdef extern from "minimap.h":
 	# Options
 	#
 	ctypedef struct mm_idxopt_t:
-		short k, w, is_hpc, bucket_bits
+		short k, w, flag, bucket_bits
 		int mini_batch_size
 		uint64_t batch_size
 
@@ -51,7 +51,7 @@ cdef extern from "minimap.h":
 		pass
 
 	ctypedef struct mm_idx_t:
-		int32_t b, w, k, is_hpc
+		int32_t b, w, k, flag
 		uint32_t n_seq
 		mm_idx_seq_t *seq
 		uint32_t *S