# Fixing punctuation after a field in biblatex

Customising a biblatex style, I want to ensure that after the title of books only a space is used. If you take a look at one of the standard drivers:

\DeclareBibliographyDriver{book}{%
\usebibmacro{bibindex}%
\usebibmacro{begentry}%
\usebibmacro{author/editor+others/translator+others}%
\setunit{\labelnamepunct}\newblock
\usebibmacro{maintitle+title}%
\newunit
\printlist{language}%
\newunit\newblock
\usebibmacro{byauthor}%
\newunit\newblock
\usebibmacro{byeditor+others}%
\newunit\newblock
\printfield{edition}%
\newunit
\iffieldundef{maintitle}
{\printfield{volume}%
\printfield{part}}
{}%
\newunit
\printfield{volumes}%
\newunit\newblock
\usebibmacro{series+number}%
\newunit\newblock
\printfield{note}%
\newunit\newblock
\usebibmacro{publisher+location+date}%
\newunit\newblock
\usebibmacro{chapter+pages}%
\newunit
\printfield{pagetotal}%
\newunit\newblock
\iftoggle{bbx:isbn}
{\printfield{isbn}}
{}%
\newunit\newblock
\usebibmacro{doi+eprint+url}%
\newunit\newblock
\setunit{\bibpagerefpunct}\newblock
\usebibmacro{pageref}%
\usebibmacro{finentry}}

\usebibmacro{maintitle+title}%

does not work as the various \newunit instructions seem to over-ride it even if no additional fields are printed. What's the correct way to say 'the next punctuation must always be just a space'?

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