Use ABAP_TRUE and ABAP_FALSE for comparisons

has_entries = abap_true.
IF has_entries = abap_false.

Don’t use the character equivalents 'X' and ' ' or space; they make it hard to see that this is a Boolean expression:

" anti-pattern
has_entries = 'X'.
IF has_entries = space.

Avoid comparisons with INITIAL - it forces readers to recollect that abap_bool’s default is abap_false:

" anti-pattern
IF has_entries IS NOT INITIAL.

ABAP may be the one single programming language that does not come with built-in “constants” for true and false. However, having them is imperative. This recommendation is based on the ABAP Programming Guidelines.