I couldn't find an online copy of the Texas Grand Commandery's Constitution, but I know Idaho's Constitution says something similar.
Once the new format of our Constitution and Statutes is approved in April, it should appear on the Grand Commandery website.
This is how the Constitution and Statutes of the Grand Commandery Knights Templar of Texas addresses the Cap and Mantle. I also added what is to be worn under the Mantle.
Art. 351. (G 41 & G 62). Uniforms.
The purchase of Knights Templar uniform by a petitioner for the Orders in this Grand Jurisdiction is optional with the petitioner.
(d) In lieu of the regulation uniform, a Constituent Commandery may provide and use the cap and mantle as their official uniform. The regulation uniform or cap and mantle may be worn for all Templar occasions, provided, however, that, when appearing in public, the entire Commandery shall be dressed in the same uniform, that is, all either in a regulation uniform or in the cap and mantle uniform. The cap and mantle uniform is authorized for use and is as prescribed in Article 354. Art. 353.
Specifications for Texas Templar Full Dress Uniform.
(b) Trousers to be cut on U. Navy pattern, zipper fly. Plain button, no cuffs, of same material as coat.
(d) Shirt to be white turndown collar.
(e) Tie to be black four-in-hand.
(g) Black shoes or black Wellington or black cowboy boots, and black hose; the trousers to be worn on the outside of the boot at all times.
Art. 354. Design and material for the Cap and Mantle Templar Uniform: The following is herein designated as proper design of the caps and mantles (ceremonial robes) now permitted as an alternative to the Uniform in the Opening and Closing of the Commandery and in the conferral of the Order of the Temple:
A. TEMPLAR MANTLE: In general, the mantle shall be of the style worn by Medieval Templars and by members of the Sovereign Great Priories. It shall consist of white material, with hood, reaching to approximately twelve inches from the floor and ornamented as follows:
1. For members of the Order below the rank of Commander:
The mantle shall be of white; the hood to be lined with silky white material; the Passion Cross in bright red, nine inches in height, on the left breast; the mantle to tie closely around the neck with white cords with white tassels.
2. For Commanders and Past Commanders:
The mantle shall have a single red ribbon, one inch wide, stitched one-half inch from the outer edge; the hood to be lined with a similar red material; the Passion Cross in red with gold rays, nine inches in height, on the left breast; the mantle to tie closely around the neck with red cords with red tassels.
3. For Grand Officers and Past Grand Officers entitled to permanent rank:
The mantle shall have the ribbon of a Past Commander and an additional red ribbon one-half inch wide, stitched one-half inch from said ribbon; the Templar Cross in red, nine inches in height, on the left breast; the mantle to tie closely around the neck with red cords and tassels.
4. For the Grand Commander:
The mantle shall have a single red ribbon, two inches wide, stitched one inch from the outer edge; the hood lined in red with a similar material; the Templar Cross in red, nine inches in height on the left breast; the mantle to tie closely around the neck with red cords and red tassels.
5. For Past Grand Commanders:
The mantle shall have a single purple ribbon, one and one-half inches wide, stitched three-quarters of an inch from the outer edge; the hood lined in purple with similar material; and the Templar Cross in purple material on the left breast, nine inches in height; the mantle to tie closely around the neck with purple cords and red tassels.
B. TEMPLAR CAP: The Templar cap shall follow the design and specifications of the style worn by the Sovereign Great Priories, three inches in depth and very slightly flared at the top.
1. For all members of the Order below the rank of Past Grand Commander:
The cap shall be of bright red velvet (or silk) and the cross displayed on the front of the cap shall be appropriate to rank -- red Passion Cross for members below the rank of Commander; red Passion Cross with gold rays for Commanders and Past Commanders; and red Templar Cross for all Grand Officers and Past Grand Officers entitled to permanent rank.
2. For Past Grand Commanders:
The cap shall be of purple velvet (or silk) with purple Templar Cross.
3. For all Ranks:
The Cross shall be two inches high.
C. COMMANDERY BADGE: The distinctive badge of a Constituent Commandery may be worn on the right breast of the mantle. The badge will be no less than five inches or more than eight inches high. The badge of the Commandery shall be superimposed upon the Malta Cross, or the Malta Cross shall be incorporated within the Commandery badge. The design shall be approved by the Grand Commandery Committee on Jewels and Uniforms. No other ornamentation or Templar jewels or recognitions shall be worn on the mantle.
D. SWORD AND SCABBARD: The sword and scabbard shall conform to the regulations of the Grand Encampment.
E. SWORD SLING: The sword shall be suspended, when required to be worn, on a sling to be worn over the right shoulder, of black leather one and one-half inches wide, of tailored or adjustable length according to the height of the Sir Knight, to terminate in two straps with snaps to fasten to the two upper rings of the scabbard.