Armor check penalty

Armor Check Penalty (ACP): The Penalty to Skills due to the restrictiveness of certain armor.

The following are subject to ACP:
 * Balance
 * Hide
 * Jump
 * Move Silently
 * Tumble
 * Swim is subject to double the standard ACP

Carrying capacity also can cause an ACP. Note that medium encumbrance does not give any visual feedback, except that you run slightly slower. This may lead to unexpected deaths while swimming.
 * Medium encumbrance causes a -3
 * Heavy encumbrance causes a -6

Non-proficiency with a certain armor or shield will apply the ACPs to all attack rolls, Strength based skills and Dexterity based skills. Non-proficiency penalties from armor and shields stack.