diff --git a/src/clib/pio.h b/src/clib/pio.h
index 38a83db62ca..83ed8f7feae 100644
--- a/src/clib/pio.h
+++ b/src/clib/pio.h
@@ -34,8 +34,13 @@
 #endif
 
 /** PIO_OFFSET is an integer type of size sufficient to represent the
- * size (in bytes) of the largest file supported by MPI. */
+ * size (in bytes) of the largest file supported by MPI. This is not
+ * actually used by the code. */
 #define PIO_OFFSET MPI_OFFSET
+
+/** PIO_OFFSET is defined as MPI_Offset, which is defined in
+ * pio_internal.h as long long. This is what is used throughout the C
+ * code. */
 #define PIO_Offset MPI_Offset
 
 /** The maximum number of variables allowed in a netCDF file. */
@@ -210,7 +215,7 @@ enum PIO_REARR_COMM_FC_DIR
     PIO_REARR_COMM_FC_2D_DISABLE
 };
 
-/* Constant to indicate unlimited requests. */
+/** Constant to indicate unlimited requests for the rearranger. */
 #define PIO_REARR_COMM_UNLIMITED_PEND_REQ -1
 
 /**
@@ -760,13 +765,16 @@ enum PIO_ERROR_HANDLERS
 #define PIO_EINDEP  (-203)
 #endif /* _PNETCDF */
 
-/** Define error codes for PIO. */
+/** The first error code for PIO. */
 #define PIO_FIRST_ERROR_CODE (-500)
+
+/** Bad IOTYPE error. */
 #define PIO_EBADIOTYPE  (-500)
-/** variable dimensions do not match in a multivar call */
+
+/** Variable dimensions do not match in a multivar call. */
 #define PIO_EVARDIMMISMATCH (-501)
 
-/** ??? */
+/** Request NULL. */
 #define PIO_REQ_NULL (NC_REQ_NULL-1)
 
 #if defined(__cplusplus)
@@ -818,11 +826,14 @@ extern "C" {
                         int *num_procs_per_comp, int **proc_list, MPI_Comm *io_comm, MPI_Comm *comp_comm,
                         int rearranger, int *iosysidp);
 
-    int PIOc_Init_Intercomm(int component_count, MPI_Comm peer_comm, MPI_Comm *comp_comms,
-                            MPI_Comm io_comm, int *iosysidp);
+    /* How many IO tasks in this iosysid? */
     int PIOc_get_numiotasks(int iosysid, int *numiotasks);
+
+    /* Initialize PIO for intracomm mode. */
     int PIOc_Init_Intracomm(MPI_Comm comp_comm, int num_iotasks, int stride, int base, int rearr,
                             int *iosysidp);
+
+    /* Shut down iosystem and free all associated resources. */
     int PIOc_finalize(int iosysid);
 
     /* Set error handling for entire io system. */
@@ -913,7 +924,6 @@ extern "C" {
                              int deflate_level);
     int PIOc_inq_var_deflate(int ncid, int varid, int *shufflep, int *deflatep,
                              int *deflate_levelp);
-    int PIOc_inq_var_szip(int ncid, int varid, int *options_maskp, int *pixels_per_blockp);
     int PIOc_def_var_chunking(int ncid, int varid, int storage, const PIO_Offset *chunksizesp);
     int PIOc_inq_var_chunking(int ncid, int varid, int *storagep, PIO_Offset *chunksizesp);
     int PIOc_def_var_endian(int ncid, int varid, int endian);
diff --git a/src/clib/pio_rearrange.c b/src/clib/pio_rearrange.c
index fe449774358..fa946c140eb 100644
--- a/src/clib/pio_rearrange.c
+++ b/src/clib/pio_rearrange.c
@@ -1344,7 +1344,6 @@ int box_rearrange_create(iosystem_desc_t *ios, int maplen, const PIO_Offset *com
     }
     if(ios->ioproc){
         /* Only I/O procs send sc_info messages */
-        int nmsgs = ios->num_iotasks;
         for (int i = 0; i < ios->num_comptasks; i++)
         {
             sendcounts[ios->compranks[i]] = sc_info_msg_sz;
diff --git a/src/clib/pioc_support.c b/src/clib/pioc_support.c
index c771e584c2d..ae94aea8f64 100644
--- a/src/clib/pioc_support.c
+++ b/src/clib/pioc_support.c
@@ -1710,7 +1710,7 @@ int PIOc_writemap_from_f90(const char *file, int ndims, const int *gdims,
  * parameters are read on comp task 0 and ignored elsewhere.
  *
  * @param iosysid A defined pio system ID, obtained from
- * PIOc_Init_Intercomm() or PIOc_InitAsync().
+ * PIOc_Init_Intracomm() or PIOc_InitAsync().
  * @param ncidp A pointer that gets the ncid of the newly created
  * file.
  * @param iotype A pointer to a pio output format. Must be one of
diff --git a/src/clib/uthash.h b/src/clib/uthash.h
index 76bdca64199..59910166f59 100644
--- a/src/clib/uthash.h
+++ b/src/clib/uthash.h
@@ -1156,6 +1156,7 @@ for(((el)=(head)), ((tmp)=DECLTYPE(el)((head!=NULL)?(head)->hh.next:NULL));
 #define HASH_COUNT(head) HASH_CNT(hh,head)
 #define HASH_CNT(hh,head) ((head != NULL)?((head)->hh.tbl->num_items):0U)
 
+/** Hash bucket. */
 typedef struct UT_hash_bucket {
    struct UT_hash_handle *hh_head;
    unsigned count;
@@ -1180,6 +1181,7 @@ typedef struct UT_hash_bucket {
 #define HASH_SIGNATURE 0xa0111fe1u
 #define HASH_BLOOM_SIGNATURE 0xb12220f2u
 
+/** Hash table. */
 typedef struct UT_hash_table {
    UT_hash_bucket *buckets;
    unsigned num_buckets, log2_num_buckets;
@@ -1213,6 +1215,7 @@ typedef struct UT_hash_table {
 
 } UT_hash_table;
 
+/** Hash handle. */
 typedef struct UT_hash_handle {
    struct UT_hash_table *tbl;
    void *prev;                       /* prev element in app order      */