====== MASK_ALPHA() :STRING ======
Returns a valid character mask for input statements of //A// through //Z// and //a// through //z//  

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**See also:** [[ppl:functions:mask_alnum|Mask_Alnum]], [[ppl:functions:mask_ascii|Mask_Ascii]], [[ppl:functions:mask_file|Mask_File]], [[ppl:functions:mask_num|Mask_Num]], [[ppl:functions:mask_path|Mask_Path]], [[ppl:functions:mask_pwd|Mask_Pwd]]