The periodical has 'rigid' [='strict', 'inflexible'] guidelines for submissions.
a 'rigid' [='strict, unwavering'] adherence to the rules
The soldiers stood 'rigidly' at attention.
(..) It's called memory cloth. Notice anything? Regularly flexible... ...but put a current through it... ...molecules realign, it becomes rigid. - What kind of shapes can you make? Can be tailored to fit any structure based on a rigid skeleton. Too expensive for the Army? (..)2005 Batman Begins