This is my first time doing an online forum.  I am studying to take the CWI exam in march. I am reading through the code to clarify things that I do not understand.  Currently, I am a certified welder at a bridge company and have graduated after two years at the local community college in Welding Technology.  I understand that the CWI exam doesn't require you to memorize the D1.1 Code from cover to cover.  It tests things such as your ability to look up the answers, your general understanding of the standards, how to measure weld sizes, and what changes require requalification.   I am posting questions that may deal with the engineering aspects of the code. I realize that I don't need to know half of the stuff I'm asking about in order to pass the CWI exam. However, I am asking them in an effort to become a more knowledgeable inspector, and hope that someone who reads these posts will be able to answer my questions. 

1. What is "undermatching" sec. 3.3
2. How does yield strength differ from specific yield strength? sec. 1.2.2
3. How do "nominal" stresses differ from "calculated" stresses? sec. 2.5.1
4. In section 2.3.1.1, the effective weld length of a groove weld is the "width of the part joined...perpendicular to the direction of the stress...regardless of the orientation." This doesn't factor in the actual length of the weld. Why?
5. Effective weld length-Fillet weld (2.3.2.1), “No reduction in effective length shall be assumed in design calculations to allow for the start or stop crater of the weld.” Does this mean calculations based on weld lengths should include the start and stop?
6. What is the difference between filler metal specification (Publication A5.20 & Annex V) vs. filler metal classification? (Table 4.13)
7. What is an end loaded fillet weld? (2.3.3.2)
8. “The calculated base-metal stresses shall not exceed the allowable stresses specified in the applicable design specifications.” (2.5.3) Isn’t this kind of obvious?
9. What are some common examples of “design eccentricity”? (2.5.2)
10. What is the difference between “effective length” and “length specified” (2.3.1.1)
11. “Allowable stress increase” where are they coming from in this rule? There is nothing on it in  the commentary. (2.5.5)
12. Is “finished to bear” the same as mill to bear? (2.6.2.1)
15. What are “local geometrical discontinuities“? (2.14.1)
16. What are “concurrent applied loads”? (2.14.2)