5 deleted 13 characters in body

# Dyalog APL, 1717 15 bytes

{100=+/17-⍨⎕AV⍳⍵}⍨⎕AV⍳⍞


Anonymous monad, usesUses the Dyalog Classic character set.

              ⍵⍞  ⍝ monadicstring argumentinput
⎕AV⍳   ⍝ index in the character map
17-⍨       ⍝ subtract 17 from each ('a' = 18)
+/           ⍝ sum
100=             ⍝ equal to 100?


# Dyalog APL, 17 bytes

{100=+/17-⍨⎕AV⍳⍵}


Anonymous monad, uses the Dyalog Classic character set.

              ⍵  ⍝ monadic argument
⎕AV⍳   ⍝ index in the character map
17-⍨       ⍝ subtract 17 from each ('a' = 18)
+/           ⍝ sum
100=             ⍝ equal to 100?


# Dyalog APL, 17 15 bytes

100=+/17-⍨⎕AV⍳⍞


Uses the Dyalog Classic character set.

              ⍞  ⍝ string input
⎕AV⍳   ⍝ index in the character map
17-⍨       ⍝ subtract 17 from each ('a' = 18)
+/           ⍝ sum
100=             ⍝ equal to 100?

4 deleted 83 characters in body

# Dyalog APL, 17 bytes

{100=+/17-⍨⎕AV⍳⍵}


Anonymous monad, uses the CP-293 encodingDyalog Classic character set.

              ⍵  ⍝ monadic argument
⎕AV⍳   ⍝ index in the character map
17-⍨       ⍝ subtract 17 from each ('a' = 18)
+/           ⍝ sum
100=             ⍝ equal to 100?


# Dyalog APL, 17 bytes

{100=+/17-⍨⎕AV⍳⍵}


Anonymous monad, uses the CP-293 encoding.

              ⍵  ⍝ monadic argument
⎕AV⍳   ⍝ index in the character map
17-⍨       ⍝ subtract 17 from each ('a' = 18)
+/           ⍝ sum
100=             ⍝ equal to 100?


# Dyalog APL, 17 bytes

{100=+/17-⍨⎕AV⍳⍵}


Anonymous monad, uses the Dyalog Classic character set.

              ⍵  ⍝ monadic argument
⎕AV⍳   ⍝ index in the character map
17-⍨       ⍝ subtract 17 from each ('a' = 18)
+/           ⍝ sum
100=             ⍝ equal to 100?

3 added 66 characters in body

# Dyalog APL, 1417 bytes

{100=+/17-⍨⎕AV⍳⍨⎕AV⍳⍵}


UsesAnonymous monad, uses the CP-293 encoding.

              ⍵  ⍝ monadic argument
⎕AV⍳   ⍝ index in the character map
17-⍨       ⍝ subtract 17 from each ('a' = 18)
+/           ⍝ sum
100=             ⍝ equal to 100?


# Dyalog APL, 14 bytes

100=+/17-⍨⎕AV⍳


Uses the CP-293 encoding.

          ⎕AV⍳  ⍝ index in the character map
17-⍨      ⍝ subtract 17 from each ('a' = 18)
+/          ⍝ sum
100=            ⍝ equal to 100?


# Dyalog APL, 17 bytes

{100=+/17-⍨⎕AV⍳⍵}


Anonymous monad, uses the CP-293 encoding.

              ⍵  ⍝ monadic argument
⎕AV⍳   ⍝ index in the character map
17-⍨       ⍝ subtract 17 from each ('a' = 18)
+/           ⍝ sum
100=             ⍝ equal to 100?

2 added 9 characters in body
1