Some notations have precise rhythm while others give none. BeatTab is a full musical notation with BOTH of the main elements of PITCH and RHYTHM yet looks much like standard Harp Tab. Even the DOWNBEATS and UPBEATS are clearly expressed. A simple notation for the easy licks — with precision features as needed for the more complex stuff. Don't be overpowered by the detail. Just go try some simple examples like Row, Row, Row Your Boat to gain clarity.
Bar (or measure): Use the forward slash ( / ) - /4 5 6 5 /5 6 4 - / = 2 bars of 4 beats each.
Hole: Hole numbers are 1,2,3 … 8,9,0 (using 0 for the 10th hole).
Rest: An ( x ) indicates a "silent" note ( 1/8 rest or stop if after note).
Modifiers: Always placed AFTER the note in the order of:
1. Pitch (direction & bending), 2. Chording (note combinations), then 3. Rhythm (durations).
Direction of airflow: Draw holes are plain ( 3 4 ), Blows underlined ( 3 4 ).
Bend: ( ' '' ''') = single/double/triple bends (2' , 3'' , 3''' or 8') - degree of bend per context.
Dip Bend: ( ` ) = (4` or 8`) - start on bent note & swoop up to the unbent tone.
Dip Bend Down: ( v ) = (2` or 8v) - start on the unbent tone & quickly bend down per context.
Overbend: ( * ) - (6* = 6 hole overblow) (7* = 7 hole overdraw).
For slides, glisses, vibrato, etc. — see 2020 Music Notation.
Chord: ( c ) Placed after the LOWER hole - (2c = 23 together - often with 3 a bit weaker).
Chord Smile: ( s ) After CENTER hole (3s = 234 together) - ie: play the 3 draw and “smile”.
Chord Tongue Block: ( t ) After main HIGHER note - (4t = 14 together - tongue covers 23).
Wide Tongue Block: ( T ) After main HIGHER note - (8T = 48 together - tongue covers 567).
Trill / Shake: ( = ) Placed AFTER 1st lower note - (4= is 4545).
All notes (& rest x’s) start with a 1/8 note default duration before Modifiers are applied.
Reference Duration (BEAT): (1/4 note duration normally) - ie: The counted beats in the bar.
Default Duration: (1/8 note normally) - All unmodified notes are 1/2 the duration of the BEAT.
Extension Modifiers for Durations:
Dashes add the default duration to itself - eg: 1/8 notes become 1/4 notes - for downbeats.
Spaces add the default duration to itself - eg: 1/8 notes become 1/4 notes - for upbeats.
Periods add the default duration to itself - like a space but more visible (good for handwriting).
Commas also add a default duration - but also "sticks" adjacent notes (holes or x's) together.
Semicolons (;) are equivalent to a period+comma (seldom used but for very small durations).
Explicit swing can be shown via [hole-space-hole] eg: [2 3] per context, OR by 2,3 whereas:
Comma's allow explicit swing rhythm (delayed notes) - eg: /2,23,34,45 / or /[2,2]3,3[4,4]5 /.
Comma’s add about 1/3 to a preceding note duration & removes 1/3 from the next note.
As commas "stick" the two adjacent notes (holes or x's) together, they then imply [ ]'s exist.
Note that Downbeats are BEFORE commas & swung Upbeats are AFTER commas.
Spaces, Dashes, etc. all ADD 1/8 durations - (eg: /2 - - - / is 1/8 + 7 more 1/8's =8/8=1).
Spaces, Dashes, etc. all act as "placeholders" thereby allowing context durations to be applied.
Contraction Modifiers for Durations:
Square Brackets: [ ] = BEAT (duration of 1/4 note) - eg:  or  or .
 indicates the same duration as 23 alone so [ ]'s are only needed so to clarify the grouping.
 would indicate a 1/8 triplet (with 3 notes played in the same duration context as the 23 alone).
 being faster 1/16 notes (4 notes played in the same duration context as the 23 alone).
Or use placeholders like commas (or semicolons for "double" placeholders) to enable other durations such as [2,,457,,] or [834567;] here showing as all 1/32 notes except for the 2 and the 7's which are 3/32 notes. Note that nested [ ] brackets can also be used (they represent a duration being one-half of the Beat brackets). However it is usually more clear to simply show durations such as [237,8,9,] using comma placeholders. Nesting is discouraged as it obscures.
Also see the chapters 5 and 6 of 2020 Music Notation for a complete detail per all of the above.
2020 Music Notation website