Formula Documentation

When I am programming in any assembler language, it is common practice to embed descriptions of what a sub-routine or command is intended to do.

Is there a way to insert documentation text into a formula without it printing on the monitor or being included in calculations within the formula itself?

For example:  This is a formula I use within a spreadsheet to help me make specific decisions using discreet known data.  The first 3 rows are column headers.  Cells A4 through AS53 is data, and Cells AT4 through BI53 are a series of decision trees.  This specific example is cell AY4.

Even though I wrote this part of the decision tree, I find it difficult to remember what each step does -- and therefore, it is difficult to edit or modify it for specific uses.

=IF($A4="","",IF($AX4="Pick",0,IF($AX4=$A4,(((IF(AND($E4=0,$F4=0),1,($D4+($F4/2))/($D4+$E4+$F4)))+$L4+$P4+$S4+($U4/10)+($V4/8)+($X4/2))/7),(((IF(AND($Z4=0,$AA4=0),1,($Y4+($AA4/2))/($Y4+$Z4+$AA4)))+$AG4+$AK4+$AN4+($AP4/10)+($AQ4/8)+($AS4/2))/7))))

How do I imbed documentation to myself -- or to others that may use this worksheet -- within (but invisible to) the formula what each element of this decision tree does?