diff --git a/pyModeS/__init__.py b/pyModeS/__init__.py
index 488cb89..3b414d0 100644
--- a/pyModeS/__init__.py
+++ b/pyModeS/__init__.py
@@ -15,8 +15,6 @@ from .decoder import bds
 from .extra import aero
 from .extra import tcpclient
 
-from .encoder import encode_adsb
-
 
 warnings.simplefilter("once", DeprecationWarning)
 
diff --git a/pyModeS/decoder/adsb.py b/pyModeS/decoder/adsb.py
index b1c8e9b..4fc95ab 100644
--- a/pyModeS/decoder/adsb.py
+++ b/pyModeS/decoder/adsb.py
@@ -47,8 +47,9 @@ def typecode(msg):
 
 
 def position(msg0, msg1, t0, t1, lat_ref=None, lon_ref=None):
-    """Decode position from a pair of even and odd position message
-    (works with both airborne and surface position messages)
+    """Decode position from a pair of even and odd position message.
+
+    Works with both airborne and surface position messages.
 
     Args:
         msg0 (string): even message (28 hexdigits)
@@ -58,6 +59,7 @@ def position(msg0, msg1, t0, t1, lat_ref=None, lon_ref=None):
 
     Returns:
         (float, float): (latitude, longitude) of the aircraft
+
     """
     tc0 = typecode(msg0)
     tc1 = typecode(msg1)
@@ -85,15 +87,16 @@ def position(msg0, msg1, t0, t1, lat_ref=None, lon_ref=None):
 
 
 def position_with_ref(msg, lat_ref, lon_ref):
-    """Decode position with only one message,
-    knowing reference nearby location, such as previously
-    calculated location, ground station, or airport location, etc.
-    Works with both airborne and surface position messages.
+    """Decode position with only one message.
+
+    A reference position is required, which can be previously
+    calculated location, ground station, or airport location.
+    The function works with both airborne and surface position messages.
     The reference position shall be with in 180NM (airborne) or 45NM (surface)
     of the true position.
 
     Args:
-        msg (string): even message (28 hexdigits)
+        msg (str): even message (28 hexdigits)
         lat_ref: previous known latitude
         lon_ref: previous known longitude
 
@@ -114,15 +117,15 @@ def position_with_ref(msg, lat_ref, lon_ref):
 
 
 def altitude(msg):
-    """Decode aircraft altitude
+    """Decode aircraft altitude.
 
     Args:
-        msg (string): 28 bytes hexadecimal message string
+        msg (str): 28 hexdigits string
 
     Returns:
         int: altitude in feet
-    """
 
+    """
     tc = typecode(msg)
 
     if tc < 5 or tc == 19 or tc > 22:
@@ -137,36 +140,31 @@ def altitude(msg):
         return altitude05(msg)
 
 
-def velocity(msg, rtn_sources=False):
-    """Calculate the speed, heading, and vertical rate
-    (handles both airborne or surface message)
+def velocity(msg, source=False):
+    """Calculate the speed, heading, and vertical rate (handles both airborne or surface message).
 
     Args:
-        msg (string): 28 bytes hexadecimal message string
-        rtn_source (boolean): If the function will return
-            the sources for direction of travel and vertical
-            rate. This will change the return value from a four
-            element array to a six element array.
+        msg (str): 28 hexdigits string
+        source (boolean): Include direction and vertical rate sources in return. Default to False.
+            If set to True, the function will return six value instead of four.
 
     Returns:
-        (int, float, int, string, string, string): speed (kt),
-            ground track or heading (degree),
-            rate of climb/descent (ft/min), speed type
-            ('GS' for ground speed, 'AS' for airspeed),
-            direction source ('true_north' for ground track / true north
-            as reference, 'mag_north' for magnetic north as reference),
-            rate of climb/descent source ('Baro' for barometer, 'GNSS'
-            for GNSS constellation).
+        int, float, int, string, [string], [string]: Four or six parameters, including:
+            - Speed (kt)
+            - Angle (degree), either ground track or heading
+            - Vertical rate (ft/min)
+            - Speed type ('GS' for ground speed, 'AS' for airspeed)
+            - [Optional] Direction source ('TRUE_NORTH' or 'MAGENTIC_NORTH')
+            - [Optional] Vertical rate source ('BARO' or 'GNSS')
+
+        For surface messages, vertical rate and its respective sources are set to None.
 
-            In the case of surface messages, None will be put in place
-            for vertical rate and its respective sources.
     """
-
     if 5 <= typecode(msg) <= 8:
-        return surface_velocity(msg, rtn_sources)
+        return surface_velocity(msg, source)
 
     elif typecode(msg) == 19:
-        return airborne_velocity(msg, rtn_sources)
+        return airborne_velocity(msg, source)
 
     else:
         raise RuntimeError(
@@ -179,7 +177,7 @@ def speed_heading(msg):
     (handles both airborne or surface message)
 
     Args:
-        msg (string): 28 bytes hexadecimal message string
+        msg (str): 28 hexdigits string
 
     Returns:
         (int, float): speed (kt), ground track or heading (degree)
@@ -191,7 +189,7 @@ def speed_heading(msg):
 def oe_flag(msg):
     """Check the odd/even flag. Bit 54, 0 for even, 1 for odd.
     Args:
-        msg (string): 28 bytes hexadecimal message string
+        msg (str): 28 hexdigits string
     Returns:
         int: 0 or 1, for even or odd frame
     """
@@ -203,7 +201,7 @@ def version(msg):
     """ADS-B Version
 
     Args:
-        msg (string): 28 bytes hexadecimal message string, TC = 31
+        msg (str): 28 hexdigits string, TC = 31
 
     Returns:
         int: version number
@@ -225,7 +223,7 @@ def nuc_p(msg):
     """Calculate NUCp, Navigation Uncertainty Category - Position (ADS-B version 1)
 
     Args:
-        msg (string): 28 bytes hexadecimal message string,
+        msg (str): 28 hexdigits string,
 
     Returns:
         int: Horizontal Protection Limit
@@ -261,7 +259,7 @@ def nuc_v(msg):
     """Calculate NUCv, Navigation Uncertainty Category - Velocity (ADS-B version 1)
 
     Args:
-        msg (string): 28 bytes hexadecimal message string,
+        msg (str): 28 hexdigits string,
 
     Returns:
         int or string: 95% Horizontal Velocity Error
@@ -290,7 +288,7 @@ def nic_v1(msg, NICs):
     """Calculate NIC, navigation integrity category, for ADS-B version 1
 
     Args:
-        msg (string): 28 bytes hexadecimal message string
+        msg (str): 28 hexdigits string
         NICs (int or string): NIC supplement
 
     Returns:
@@ -324,7 +322,7 @@ def nic_v2(msg, NICa, NICbc):
     """Calculate NIC, navigation integrity category, for ADS-B version 2
 
     Args:
-        msg (string): 28 bytes hexadecimal message string
+        msg (str): 28 hexdigits string
         NICa (int or string): NIC supplement - A
         NICbc (int or srting): NIC supplement - B or C
 
@@ -362,7 +360,7 @@ def nic_s(msg):
     """Obtain NIC supplement bit, TC=31 message
 
     Args:
-        msg (string): 28 bytes hexadecimal message string
+        msg (str): 28 hexdigits string
 
     Returns:
         int: NICs number (0 or 1)
@@ -384,7 +382,7 @@ def nic_a_c(msg):
     """Obtain NICa/c, navigation integrity category supplements a and c
 
     Args:
-        msg (string): 28 bytes hexadecimal message string
+        msg (str): 28 hexdigits string
 
     Returns:
         (int, int): NICa and NICc number (0 or 1)
@@ -407,7 +405,7 @@ def nic_b(msg):
     """Obtain NICb, navigation integrity category supplement-b
 
     Args:
-        msg (string): 28 bytes hexadecimal message string
+        msg (str): 28 hexdigits string
 
     Returns:
         int: NICb number (0 or 1)
@@ -429,7 +427,7 @@ def nac_p(msg):
     """Calculate NACp, Navigation Accuracy Category - Position
 
     Args:
-        msg (string): 28 bytes hexadecimal message string, TC = 29 or 31
+        msg (str): 28 hexdigits string, TC = 29 or 31
 
     Returns:
         int or string: 95% horizontal accuracy bounds, Estimated Position Uncertainty
@@ -464,7 +462,7 @@ def nac_v(msg):
     """Calculate NACv, Navigation Accuracy Category - Velocity
 
     Args:
-        msg (string): 28 bytes hexadecimal message string, TC = 19
+        msg (str): 28 hexdigits string, TC = 19
 
     Returns:
         int or string: 95% horizontal accuracy bounds for velocity, Horizontal Figure of Merit
@@ -493,7 +491,7 @@ def sil(msg, version):
     """Calculate SIL, Surveillance Integrity Level
 
     Args:
-        msg (string): 28 bytes hexadecimal message string with TC = 29, 31
+        msg (str): 28 hexdigits string with TC = 29, 31
 
     Returns:
         int or string: Probability of exceeding Horizontal Radius of Containment RCu
diff --git a/pyModeS/decoder/bds/__init__.py b/pyModeS/decoder/bds/__init__.py
index d6e0163..f3ed2d2 100644
--- a/pyModeS/decoder/bds/__init__.py
+++ b/pyModeS/decoder/bds/__init__.py
@@ -45,7 +45,7 @@ def is50or60(msg, spd_ref, trk_ref, alt_ref):
     """Use reference ground speed and trk to determine BDS50 and DBS60.
 
     Args:
-        msg (String): 28 bytes hexadecimal message string
+        msg (str): 28 hexdigits string
         spd_ref (float): reference speed (ADS-B ground speed), kts
         trk_ref (float): reference track (ADS-B track angle), deg
         alt_ref (float): reference altitude (ADS-B altitude), ft
@@ -108,7 +108,7 @@ def infer(msg, mrar=False):
     """Estimate the most likely BDS code of an message.
 
     Args:
-        msg (String): 28 bytes hexadecimal message string
+        msg (str): 28 hexdigits string
         mrar (bool): Also infer MRAR (BDS 44) and MHR (BDS 45). Defaults to False.
 
     Returns:
diff --git a/pyModeS/decoder/bds/bds05.py b/pyModeS/decoder/bds/bds05.py
index 29be27a..63f4081 100644
--- a/pyModeS/decoder/bds/bds05.py
+++ b/pyModeS/decoder/bds/bds05.py
@@ -85,7 +85,7 @@ def airborne_position_with_ref(msg, lat_ref, lon_ref):
     be with in 180NM of the true position.
 
     Args:
-        msg (string): even message (28 hexdigits)
+        msg (str): even message (28 hexdigits)
         lat_ref: previous known latitude
         lon_ref: previous known longitude
 
@@ -127,7 +127,7 @@ def altitude(msg):
     """Decode aircraft altitude
 
     Args:
-        msg (string): 28 bytes hexadecimal message string
+        msg (str): 28 hexdigits string
 
     Returns:
         int: altitude in feet
diff --git a/pyModeS/decoder/bds/bds06.py b/pyModeS/decoder/bds/bds06.py
index 81ab79d..2c366ce 100644
--- a/pyModeS/decoder/bds/bds06.py
+++ b/pyModeS/decoder/bds/bds06.py
@@ -1,7 +1,7 @@
 # ------------------------------------------
 #   BDS 0,6
 #   ADS-B TC=5-8
-#   Surface position
+#   Surface movment
 # ------------------------------------------
 
 from pyModeS import common
@@ -89,7 +89,7 @@ def surface_position_with_ref(msg, lat_ref, lon_ref):
     be with in 45NM of the true position.
 
     Args:
-        msg (string): even message (28 hexdigits)
+        msg (str): even message (28 hexdigits)
         lat_ref: previous known latitude
         lon_ref: previous known longitude
 
@@ -127,23 +127,24 @@ def surface_position_with_ref(msg, lat_ref, lon_ref):
     return round(lat, 5), round(lon, 5)
 
 
-def surface_velocity(msg, rtn_sources=False):
-    """Decode surface velocity from from a surface position message
+def surface_velocity(msg, source=False):
+    """Decode surface velocity from a surface position message
+
     Args:
-        msg (string): 28 bytes hexadecimal message string
-        rtn_source (boolean): If the function will return
-            the sources for direction of travel and vertical
-            rate. This will change the return value from a four
-            element array to a six element array.
+        msg (str): 28 hexdigits string
+        source (boolean): Include direction and vertical rate sources in return. Default to False.
+            If set to True, the function will return six value instead of four.
 
     Returns:
-        (int, float, int, string, string, None): speed (kt),
-            ground track (degree), None for rate of climb/descend (ft/min),
-            and speed type ('GS' for ground speed), direction source
-            ('true_north' for ground track / true north as reference),
-            None rate of climb/descent source.
-    """
+        int, float, int, string, [string], [string]: Four or six parameters, including:
+            - Speed (kt)
+            - Angle (degree), ground track
+            - Vertical rate, always 0
+            - Speed type ('GS' for ground speed, 'AS' for airspeed)
+            - [Optional] Direction source ('TRUE_NORTH')
+            - [Optional] Vertical rate source (None)
 
+    """
     if common.typecode(msg) < 5 or common.typecode(msg) > 8:
         raise RuntimeError("%s: Not a surface message, expecting 5<TC<8" % msg)
 
@@ -174,7 +175,7 @@ def surface_velocity(msg, rtn_sources=False):
         spd = kts[i - 1] + (mov - movs[i - 1]) * step
         spd = round(spd, 2)
 
-    if rtn_sources:
-        return spd, trk, 0, "GS", "true_north", None
+    if source:
+        return spd, trk, 0, "GS", "TRUE_NORTH", None
     else:
         return spd, trk, 0, "GS"
diff --git a/pyModeS/decoder/bds/bds08.py b/pyModeS/decoder/bds/bds08.py
index 3639c6f..efacab6 100644
--- a/pyModeS/decoder/bds/bds08.py
+++ b/pyModeS/decoder/bds/bds08.py
@@ -11,7 +11,7 @@ def category(msg):
     """Aircraft category number
 
     Args:
-        msg (string): 28 bytes hexadecimal message string
+        msg (str): 28 hexdigits string
 
     Returns:
         int: category number
@@ -29,7 +29,7 @@ def callsign(msg):
     """Aircraft callsign
 
     Args:
-        msg (string): 28 bytes hexadecimal message string
+        msg (str): 28 hexdigits string
 
     Returns:
         string: callsign
diff --git a/pyModeS/decoder/bds/bds09.py b/pyModeS/decoder/bds/bds09.py
index 8ed93a9..43acf00 100644
--- a/pyModeS/decoder/bds/bds09.py
+++ b/pyModeS/decoder/bds/bds09.py
@@ -10,27 +10,24 @@ from pyModeS import common
 import math
 
 
-def airborne_velocity(msg, rtn_sources=False):
-    """Calculate the speed, track (or heading), and vertical rate
+def airborne_velocity(msg, source=False):
+    """Decode airborne velocity.
 
     Args:
-        msg (string): 28 bytes hexadecimal message string
-        rtn_source (boolean): If the function will return
-            the sources for direction of travel and vertical
-            rate. This will change the return value from a four
-            element array to a six element array.
+        msg (str): 28 hexdigits string
+        source (boolean): Include direction and vertical rate sources in return. Default to False.
+            If set to True, the function will return six value instead of four.
 
     Returns:
-        (int, float, int, string, string, string): speed (kt),
-            ground track or heading (degree),
-            rate of climb/descent (ft/min), speed type
-            ('GS' for ground speed, 'AS' for airspeed),
-            direction source ('true_north' for ground track / true north
-            as reference, 'mag_north' for magnetic north as reference),
-            rate of climb/descent source ('Baro' for barometer, 'GNSS'
-            for GNSS constellation).
-    """
+        int, float, int, string, [string], [string]: Four or six parameters, including:
+            - Speed (kt)
+            - Angle (degree), either ground track or heading
+            - Vertical rate (ft/min)
+            - Speed type ('GS' for ground speed, 'AS' for airspeed)
+            - [Optional] Direction source ('TRUE_NORTH' or 'MAGENTIC_NORTH')
+            - [Optional] Vertical rate source ('BARO' or 'GNSS')
 
+    """
     if common.typecode(msg) != 19:
         raise RuntimeError("%s: Not a airborne velocity message, expecting TC=19" % msg)
 
@@ -62,9 +59,9 @@ def airborne_velocity(msg, rtn_sources=False):
         trk = math.degrees(trk)  # convert to degrees
         trk = trk if trk >= 0 else trk + 360  # no negative val
 
-        tag = "GS"
+        spd_type = "GS"
         trk_or_hdg = round(trk, 2)
-        dir_type = "true_north"
+        dir_type = "TRUE_NORTH"
 
     else:
         if mb[13] == "0":
@@ -81,32 +78,33 @@ def airborne_velocity(msg, rtn_sources=False):
             spd *= 4
 
         if mb[24] == "0":
-            tag = "IAS"
+            spd_type = "IAS"
         else:
-            tag = "TAS"
+            spd_type = "TAS"
 
-        dir_type = "mag_north"
+        dir_type = "MAGENTIC_NORTH"
 
-    vr_source = "GNSS" if mb[35] == "0" else "Baro"
+    vr_source = "GNSS" if mb[35] == "0" else "BARO"
     vr_sign = -1 if mb[36] == "1" else 1
     vr = common.bin2int(mb[37:46])
-    rocd = None if vr == 0 else int(vr_sign * (vr - 1) * 64)
+    vs = None if vr == 0 else int(vr_sign * (vr - 1) * 64)
 
-    if rtn_sources:
-        return spd, trk_or_hdg, rocd, tag, dir_type, vr_source
+    if source:
+        return spd, trk_or_hdg, vs, spd_type, dir_type, vr_source
     else:
-        return spd, trk_or_hdg, rocd, tag
+        return spd, trk_or_hdg, vs, spd_type
 
 
 def altitude_diff(msg):
-    """Decode the differece between GNSS and barometric altitude
+    """Decode the differece between GNSS and barometric altitude.
 
     Args:
-        msg (string): 28 bytes hexadecimal message string, TC=19
+        msg (str): 28 hexdigits string, TC=19
 
     Returns:
-        int: Altitude difference in ft. Negative value indicates GNSS altitude
-            below barometric altitude.
+        int: Altitude difference in feet. Negative value indicates GNSS altitude
+        below barometric altitude.
+
     """
     tc = common.typecode(msg)
 
diff --git a/pyModeS/decoder/bds/bds10.py b/pyModeS/decoder/bds/bds10.py
index abaa974..b903bcb 100644
--- a/pyModeS/decoder/bds/bds10.py
+++ b/pyModeS/decoder/bds/bds10.py
@@ -10,7 +10,7 @@ def is10(msg):
     """Check if a message is likely to be BDS code 1,0
 
     Args:
-        msg (String): 28 bytes hexadecimal message string
+        msg (str): 28 hexdigits string
 
     Returns:
         bool: True or False
@@ -42,7 +42,7 @@ def ovc10(msg):
     """Return the overlay control capability
 
     Args:
-        msg (String): 28 bytes hexadecimal message string
+        msg (str): 28 hexdigits string
 
     Returns:
         int: Whether the transponder is OVC capable
diff --git a/pyModeS/decoder/bds/bds17.py b/pyModeS/decoder/bds/bds17.py
index 5a056c9..cb5270a 100644
--- a/pyModeS/decoder/bds/bds17.py
+++ b/pyModeS/decoder/bds/bds17.py
@@ -10,7 +10,7 @@ def is17(msg):
     """Check if a message is likely to be BDS code 1,7
 
     Args:
-        msg (String): 28 bytes hexadecimal message string
+        msg (str): 28 hexdigits string
 
     Returns:
         bool: True or False
@@ -42,7 +42,7 @@ def cap17(msg):
     """Extract capacities from BDS 1,7 message
 
     Args:
-        msg (String): 28 bytes hexadecimal message string
+        msg (str): 28 hexdigits string
 
     Returns:
         list: list of support BDS codes
diff --git a/pyModeS/decoder/bds/bds20.py b/pyModeS/decoder/bds/bds20.py
index 60eb94e..d30cdd4 100644
--- a/pyModeS/decoder/bds/bds20.py
+++ b/pyModeS/decoder/bds/bds20.py
@@ -10,7 +10,7 @@ def is20(msg):
     """Check if a message is likely to be BDS code 2,0
 
     Args:
-        msg (String): 28 bytes hexadecimal message string
+        msg (str): 28 hexdigits string
 
     Returns:
         bool: True or False
@@ -36,7 +36,7 @@ def cs20(msg):
     """Aircraft callsign
 
     Args:
-        msg (String): 28 bytes hexadecimal message (BDS40) string
+        msg (str): 28 hexdigits (BDS40) string
 
     Returns:
         string: callsign, max. 8 chars
diff --git a/pyModeS/decoder/bds/bds30.py b/pyModeS/decoder/bds/bds30.py
index a71eaeb..7270d3c 100644
--- a/pyModeS/decoder/bds/bds30.py
+++ b/pyModeS/decoder/bds/bds30.py
@@ -10,7 +10,7 @@ def is30(msg):
     """Check if a message is likely to be BDS code 2,0
 
     Args:
-        msg (String): 28 bytes hexadecimal message string
+        msg (str): 28 hexdigits string
 
     Returns:
         bool: True or False
diff --git a/pyModeS/decoder/bds/bds40.py b/pyModeS/decoder/bds/bds40.py
index aca5613..9ba83a1 100644
--- a/pyModeS/decoder/bds/bds40.py
+++ b/pyModeS/decoder/bds/bds40.py
@@ -11,7 +11,7 @@ def is40(msg):
     """Check if a message is likely to be BDS code 4,0
 
     Args:
-        msg (String): 28 bytes hexadecimal message string
+        msg (str): 28 hexdigits string
 
     Returns:
         bool: True or False
@@ -54,7 +54,7 @@ def selalt40mcp(msg):
     """Selected altitude, MCP/FCU
 
     Args:
-        msg (String): 28 bytes hexadecimal message (BDS40) string
+        msg (str): 28 hexdigits (BDS40) string
 
     Returns:
         int: altitude in feet
@@ -72,7 +72,7 @@ def selalt40fms(msg):
     """Selected altitude, FMS
 
     Args:
-        msg (String): 28 bytes hexadecimal message (BDS40) string
+        msg (str): 28 hexdigits (BDS40) string
 
     Returns:
         int: altitude in feet
@@ -90,7 +90,7 @@ def p40baro(msg):
     """Barometric pressure setting
 
     Args:
-        msg (String): 28 bytes hexadecimal message (BDS40) string
+        msg (str): 28 hexdigits (BDS40) string
 
     Returns:
         float: pressure in millibar
diff --git a/pyModeS/decoder/bds/bds44.py b/pyModeS/decoder/bds/bds44.py
index 7e04de4..a2198a3 100644
--- a/pyModeS/decoder/bds/bds44.py
+++ b/pyModeS/decoder/bds/bds44.py
@@ -12,7 +12,7 @@ def is44(msg):
     Meteorological routine air report
 
     Args:
-        msg (String): 28 bytes hexadecimal message string
+        msg (str): 28 hexdigits string
 
     Returns:
         bool: True or False
@@ -55,7 +55,7 @@ def wind44(msg):
     """Wind speed and direction.
 
     Args:
-        msg (String): 28 bytes hexadecimal message string
+        msg (str): 28 hexdigits string
 
     Returns:
         (int, float): speed (kt), direction (degree)
@@ -77,7 +77,7 @@ def temp44(msg):
     """Static air temperature.
 
     Args:
-        msg (String): 28 bytes hexadecimal message string
+        msg (str): 28 hexdigits string
 
     Returns:
         float, float: temperature and alternative temperature in Celsius degree.
@@ -106,7 +106,7 @@ def p44(msg):
     """Static pressure.
 
     Args:
-        msg (String): 28 bytes hexadecimal message string
+        msg (str): 28 hexdigits string
 
     Returns:
         int: static pressure in hPa
@@ -126,7 +126,7 @@ def hum44(msg):
     """humidity
 
     Args:
-        msg (String): 28 bytes hexadecimal message string
+        msg (str): 28 hexdigits string
 
     Returns:
         float: percentage of humidity, [0 - 100] %
@@ -145,7 +145,7 @@ def turb44(msg):
     """Turblence.
 
     Args:
-        msg (String): 28 bytes hexadecimal message string
+        msg (str): 28 hexdigits string
 
     Returns:
         int: turbulence level. 0=NIL, 1=Light, 2=Moderate, 3=Severe
diff --git a/pyModeS/decoder/bds/bds45.py b/pyModeS/decoder/bds/bds45.py
index f740457..8dca85c 100644
--- a/pyModeS/decoder/bds/bds45.py
+++ b/pyModeS/decoder/bds/bds45.py
@@ -12,7 +12,7 @@ def is45(msg):
     Meteorological hazard report
 
     Args:
-        msg (String): 28 bytes hexadecimal message string
+        msg (str): 28 hexdigits string
 
     Returns:
         bool: True or False
@@ -64,7 +64,7 @@ def turb45(msg):
     """Turbulence.
 
     Args:
-        msg (String): 28 bytes hexadecimal message string
+        msg (str): 28 hexdigits string
 
     Returns:
         int: Turbulence level. 0=NIL, 1=Light, 2=Moderate, 3=Severe
@@ -82,7 +82,7 @@ def ws45(msg):
     """Wind shear.
 
     Args:
-        msg (String): 28 bytes hexadecimal message string
+        msg (str): 28 hexdigits string
 
     Returns:
         int: Wind shear level. 0=NIL, 1=Light, 2=Moderate, 3=Severe
@@ -100,7 +100,7 @@ def mb45(msg):
     """Microburst.
 
     Args:
-        msg (String): 28 bytes hexadecimal message string
+        msg (str): 28 hexdigits string
 
     Returns:
         int: Microburst level. 0=NIL, 1=Light, 2=Moderate, 3=Severe
@@ -118,7 +118,7 @@ def ic45(msg):
     """Icing.
 
     Args:
-        msg (String): 28 bytes hexadecimal message string
+        msg (str): 28 hexdigits string
 
     Returns:
         int: Icing level. 0=NIL, 1=Light, 2=Moderate, 3=Severe
@@ -136,7 +136,7 @@ def wv45(msg):
     """Wake vortex.
 
     Args:
-        msg (String): 28 bytes hexadecimal message string
+        msg (str): 28 hexdigits string
 
     Returns:
         int: Wake vortex level. 0=NIL, 1=Light, 2=Moderate, 3=Severe
@@ -154,7 +154,7 @@ def temp45(msg):
     """Static air temperature.
 
     Args:
-        msg (String): 28 bytes hexadecimal message string
+        msg (str): 28 hexdigits string
 
     Returns:
         float: tmeperature in Celsius degree
@@ -178,7 +178,7 @@ def p45(msg):
     """Average static pressure.
 
     Args:
-        msg (String): 28 bytes hexadecimal message string
+        msg (str): 28 hexdigits string
 
     Returns:
         int: static pressure in hPa
@@ -195,7 +195,7 @@ def rh45(msg):
     """Radio height.
 
     Args:
-        msg (String): 28 bytes hexadecimal message string
+        msg (str): 28 hexdigits string
 
     Returns:
         int: radio height in ft
diff --git a/pyModeS/decoder/bds/bds50.py b/pyModeS/decoder/bds/bds50.py
index 2a16999..fc2f52b 100644
--- a/pyModeS/decoder/bds/bds50.py
+++ b/pyModeS/decoder/bds/bds50.py
@@ -11,7 +11,7 @@ def is50(msg):
     (Track and turn report)
 
     Args:
-        msg (String): 28 bytes hexadecimal message string
+        msg (str): 28 hexdigits string
 
     Returns:
         bool: True or False
@@ -61,7 +61,7 @@ def roll50(msg):
     """Roll angle, BDS 5,0 message
 
     Args:
-        msg (String): 28 bytes hexadecimal message (BDS50) string
+        msg (str): 28 hexdigits (BDS50) string
 
     Returns:
         float: angle in degrees,
@@ -86,7 +86,7 @@ def trk50(msg):
     """True track angle, BDS 5,0 message
 
     Args:
-        msg (String): 28 bytes hexadecimal message (BDS50) string
+        msg (str): 28 hexdigits (BDS50) string
 
     Returns:
         float: angle in degrees to true north (from 0 to 360)
@@ -115,7 +115,7 @@ def gs50(msg):
     """Ground speed, BDS 5,0 message
 
     Args:
-        msg (String): 28 bytes hexadecimal message (BDS50) string
+        msg (str): 28 hexdigits (BDS50) string
 
     Returns:
         int: ground speed in knots
@@ -133,7 +133,7 @@ def rtrk50(msg):
     """Track angle rate, BDS 5,0 message
 
     Args:
-        msg (String): 28 bytes hexadecimal message (BDS50) string
+        msg (str): 28 hexdigits (BDS50) string
 
     Returns:
         float: angle rate in degrees/second
@@ -159,7 +159,7 @@ def tas50(msg):
     """Aircraft true airspeed, BDS 5,0 message
 
     Args:
-        msg (String): 28 bytes hexadecimal message (BDS50) string
+        msg (str): 28 hexdigits (BDS50) string
 
     Returns:
         int: true airspeed in knots
diff --git a/pyModeS/decoder/bds/bds53.py b/pyModeS/decoder/bds/bds53.py
index 34e98ca..452c405 100644
--- a/pyModeS/decoder/bds/bds53.py
+++ b/pyModeS/decoder/bds/bds53.py
@@ -11,7 +11,7 @@ def is53(msg):
     (Air-referenced state vector)
 
     Args:
-        msg (String): 28 bytes hexadecimal message string
+        msg (str): 28 hexdigits string
 
     Returns:
         bool: True or False
@@ -62,7 +62,7 @@ def hdg53(msg):
     """Magnetic heading, BDS 5,3 message
 
     Args:
-        msg (String): 28 bytes hexadecimal message (BDS53) string
+        msg (str): 28 hexdigits (BDS53) string
 
     Returns:
         float: angle in degrees to true north (from 0 to 360)
@@ -91,7 +91,7 @@ def ias53(msg):
     """Indicated airspeed, DBS 5,3 message
 
     Args:
-        msg (String): 28 bytes hexadecimal message
+        msg (str): 28 hexdigits
 
     Returns:
         int: indicated arispeed in knots
@@ -109,7 +109,7 @@ def mach53(msg):
     """MACH number, DBS 5,3 message
 
     Args:
-        msg (String): 28 bytes hexadecimal message
+        msg (str): 28 hexdigits
 
     Returns:
         float: MACH number
@@ -127,7 +127,7 @@ def tas53(msg):
     """Aircraft true airspeed, BDS 5,3 message
 
     Args:
-        msg (String): 28 bytes hexadecimal message
+        msg (str): 28 hexdigits
 
     Returns:
         float: true airspeed in knots
@@ -145,7 +145,7 @@ def vr53(msg):
     """Vertical rate
 
     Args:
-        msg (String): 28 bytes hexadecimal message (BDS60) string
+        msg (str): 28 hexdigits (BDS60) string
 
     Returns:
         int: vertical rate in feet/minutes
diff --git a/pyModeS/decoder/bds/bds60.py b/pyModeS/decoder/bds/bds60.py
index e2074fa..b02595a 100644
--- a/pyModeS/decoder/bds/bds60.py
+++ b/pyModeS/decoder/bds/bds60.py
@@ -10,7 +10,7 @@ def is60(msg):
     """Check if a message is likely to be BDS code 6,0
 
     Args:
-        msg (String): 28 bytes hexadecimal message string
+        msg (str): 28 hexdigits string
 
     Returns:
         bool: True or False
@@ -61,7 +61,7 @@ def hdg60(msg):
     """Megnetic heading of aircraft
 
     Args:
-        msg (String): 28 bytes hexadecimal message (BDS60) string
+        msg (str): 28 hexdigits (BDS60) string
 
     Returns:
         float: heading in degrees to megnetic north (from 0 to 360)
@@ -90,7 +90,7 @@ def ias60(msg):
     """Indicated airspeed
 
     Args:
-        msg (String): 28 bytes hexadecimal message (BDS60) string
+        msg (str): 28 hexdigits (BDS60) string
 
     Returns:
         int: indicated airspeed in knots
@@ -108,7 +108,7 @@ def mach60(msg):
     """Aircraft MACH number
 
     Args:
-        msg (String): 28 bytes hexadecimal message (BDS60) string
+        msg (str): 28 hexdigits (BDS60) string
 
     Returns:
         float: MACH number
@@ -126,7 +126,7 @@ def vr60baro(msg):
     """Vertical rate from barometric measurement, this value may be very noisy.
 
     Args:
-        msg (String): 28 bytes hexadecimal message (BDS60) string
+        msg (str): 28 hexdigits (BDS60) string
 
     Returns:
         int: vertical rate in feet/minutes
@@ -152,7 +152,7 @@ def vr60ins(msg):
     """Vertical rate measurd by onbard equiments (IRS, AHRS)
 
     Args:
-        msg (String): 28 bytes hexadecimal message (BDS60) string
+        msg (str): 28 hexdigits (BDS60) string
 
     Returns:
         int: vertical rate in feet/minutes