Shortforms can be confusing when they appear in longer words. Abbreviations, initialisms, and acronyms can be considered "longer words," and can often be overlooked when just a few letters at the beginning in print would represent shortforms in the longer word in braille. Using grade 1 is only required in cases where the group of letters beginning a sequence could be misread as a shortform in braille. Hopefully, we can provide a little clarity.
The UEB Literary Committee's focus in dealing with shortforms in longer words is the UEB Appendix 1 Shortform List, —often simply referred to as "The List." We also referred to §10.9.3 for words not appearing on the the List. We have studied the abbreviations you provided and provided an answer to each:
BLT would read "BLINDT" which is not on the Appendix 1 Shortform List, so we refer to §10.9.3(c) —for words not on the List —which says you may use "bl" for "blind" when it begins the word and is not followed by a vowel or a "y". So, in this example, you DO use a grade 1 indicator:
ACA would only read "ACA" since "accordinga" is not on the List and not affected by §10.9.3 (shortforms not appearing on the shortform list). In this example, you do NOT need a grade 1 indicator:
CDL would only read "CDL" since "couldl" is not on the List nor one of the ten shortforms listed in §10.9.3. (If the abbreviation was CDA, then you do use the shortform In this example since "coulda" is on the List.) However, you do NOT use a grade 1 indicator for CDL:
AFDC and AFL-CIO would only read "AFDC" and "AFL-CIO" since "afterdc" and "afterl" are not on the List nor affected by §10.9.3 (for words not appearing on the shortform list).
There is some confusion about the "Rules for list construction" that follows the Appendix 1 List. #4 refers to after, blind, and friend, and says "When the shortform for 'after,' 'blind' or 'friend' is part of a longer word and is followed by a vowel or a 'y', do not add the longer word to the Shortforms List. That doesn't mean you may use these three if not followed by a vowel or 'y' in longer words. The longer word must still appear in the List in Appendix 1.
"List construction" is only approved by the ICEB Code Maintenance Committee, which is the only body that may add words to the List . You may not use "after" in a longer word that doesn't appear on the List. So, you do not need a grade 1 indicator for AFDC nor AFL-CIO:
We hope this adds a little more clarity If you have any other questions or you need more information, please let us know.