accordeon standard bass fingering (abcm2ps)

[erch]

Hello all.

This is my first posting. I hope I searched this forum and the web carefully enough, but I didn't find an answer after well ahem hours.

Writing accordeon music with abcm2ps under linux, I'd like to write the fingering of the bass line as well. I know that fingering is inserted with !number!, e.g.

V:2 clef=bass
!4!C !3!G !2!D !5!F

But how do I write the fingering of the second bass row? In printed sheet music the number of the finger is underlined so that this is clear, e.g.

!4!C !2!D !_4!E !5!F !3!G !_5!A !_3! B !4!C

Thanks in advance,

erch

[erch]

Excuse me, by mistake I hit the "send" button to early.

The example !_3! above does not work, nor does any of the tricks I tried.

The question is:
Is it possible to underline a number in the fingering, the way it is used in accordeon notation?

Thanks, erch