<s>
DiffEngineX	B-Application
compares	O
two	O
Excel	O
spreadsheets	B-Application
and	O
reports	O
their	O
differences	O
.	O
</s>
<s>
It	O
compares	O
cells	O
(	O
formulae	O
,	O
constants	O
and	O
calculated	O
values	O
)	O
,	O
comments	O
,	O
defined	O
ranges	O
(	O
names	O
)	O
and	O
Visual	B-Language
Basic	I-Language
for	I-Language
Applications	I-Language
(	O
VBA	B-Language
)	O
macros	O
.	O
</s>
<s>
Before	O
a	O
cell-by-cell	O
comparison	O
,	O
similar	O
rows	O
and	O
columns	O
between	O
two	O
spreadsheets	B-Application
have	O
to	O
be	O
aligned	O
by	O
the	O
insertion	O
of	O
blank	O
rows/columns	O
.	O
</s>
<s>
A	O
spreadsheet	B-Application
is	O
essentially	O
a	O
grid	O
made	O
up	O
of	O
rows	O
and	O
columns	O
.	O
</s>
<s>
Before	O
spreadsheet	B-Application
comparison	O
DiffEngineX	B-Application
aligns	O
rows	O
and	O
columns	O
to	O
ensure	O
no	O
spurious	O
differences	O
are	O
reported	O
.	O
</s>
<s>
Tools	O
that	O
compare	O
Excel	O
spreadsheets	B-Application
not	O
only	O
have	O
to	O
contend	O
with	O
comparing	O
the	O
worksheet	O
cells	O
,	O
but	O
also	O
cell	O
comments	O
,	O
defined	O
ranges	O
(	O
names	O
)	O
and	O
embedded	O
Visual	O
Basic	O
for	O
Application	O
(	O
VBA	B-Language
)	O
macros	O
.	O
</s>
<s>
If	O
the	O
cell	O
contains	O
a	O
formula	O
,	O
DiffEngineX	B-Application
allows	O
the	O
user	O
a	O
choice	O
between	O
comparing	O
the	O
actual	O
text	O
of	O
the	O
formula	O
or	O
its	O
calculated	O
value	O
.	O
</s>
<s>
If	O
the	O
rows	O
are	O
pre-sorted	O
,	O
DiffEngineX	B-Application
can	O
correctly	O
compare	O
them	O
when	O
row	O
alignment	O
is	O
selected	O
.	O
</s>
<s>
DiffEngineX	B-Application
requires	O
the	O
user	O
to	O
specify	O
columns	O
that	O
act	O
as	O
unique	O
row	O
identifiers	O
.	O
</s>
<s>
For	O
these	O
cases	O
,	O
DiffEngineX	B-Application
must	O
insert	O
blank	O
rows	O
not	O
just	O
to	O
align	O
similar	O
rows	O
,	O
but	O
to	O
ensure	O
mismatched	O
rows	O
(	O
with	O
different	O
identifiers	O
)	O
end	O
up	O
paired	O
with	O
blanks	O
.	O
</s>
<s>
DiffEngineX	B-Application
's	O
row	O
alignment	O
algorithm	O
runs	O
in	O
m	O
log	O
n	O
time	O
,	O
where	O
m	O
and	O
n	O
refer	O
to	O
the	O
number	O
of	O
rows	O
in	O
the	O
two	O
spreadsheets	B-Application
being	O
compared	O
.	O
</s>
<s>
Typically	O
longest	O
common	O
subsequence	O
problem	O
algorithms	O
run	O
in	O
quadratic	O
time	O
and	O
as	O
such	O
would	O
be	O
ill-suited	O
to	O
comparing	O
spreadsheets	B-Application
with	O
hundreds	O
of	O
thousands	O
of	O
rows	O
.	O
</s>
