\begin{definition}[Definition:Sheaf of Modules Presented By Global Sections]
Let $\struct {X, \OO_X}$ be a ringed space.
A sheaf of modules $\FF$ over $\OO_X$ is '''presented by global sections''', if there are sets $I$ and $J$ and a short exact sequence
::$\begin{xy}\xymatrix@L+2mu@+1em{
\bigoplus_I \OO_X \ar[r] & \bigoplus_J \OO_X \ar[r] & \FF \ar[r] & 0
}\end{xy}$
in the category of $\OO_X$-modules.
\end{definition}